With less than two weeks until the start of the NBA regular season, the uncertainty around Brooklyn Nets guard Kyrie Irving continues to swirl.

The Nets listed Irving, 29, as ineligible to play in Friday's preseason game against the defending champion Milwaukee Bucks. New York City's COVID-19 protocols allow only NBA players with at least one vaccination shot to practice. He could play Monday when the Nets play an exhibition game at the Philadelphia 76ers.

Irving, who practiced with the Nets at their training camp in San Diego last week, has missed three days of preseason practices with his team in Brooklyn. Unable to attend media day last week at Barclays Center, Irving joined via videoconference from his home and asked for privacy.

The latest twist in this saga came Friday afternoon, when New York City deemed Irving could, in fact, practice at the team's facility moving forward, saying it is a private workplace. He still, however, cannot play in games, as Barclays Center is a public space.

The Nets, according to sources, remain unclear on Irving's intentions for getting vaccinated, and the organization has made no decision, as of Thursday, on whether it will accommodate him as a part-time player this season.

There are numerous unknowns. Most notably: How, if at all, the Nets, who are projected by ESPN's latest win-loss predictions to win 58 games, and their seven-time All-Star guard can work together prior to the start of Brooklyn's season opener versus the Bucks on Oct. 19 in Milwaukee (7:30 p.m. ET, TNT).

Here's everything we know and don't know about Irving, the Nets and how the next few weeks (or months) might play out:

How are the Nets players and coaches handling Irving's absence?

Irving's teammates are remaining hopeful and offering support, without wading into a position on the guard's vaccination stance. Kevin Durant said Wednesday he still envisions Irving joining the Nets soon.

"Maybe I'm just naïve, but that is just how I feel. ... [Kyrie] is dealing with something personal right now. And while he is dealing with that, we are going to focus on us here in the gym and keep working. When they are ready to figure that out, he'll figure it out."

Said James Harden on Thursday: "We'll keep treading water. Every single day we focus on things that we can control, things we can get better at. ... Whatever happens, happens. I want him to be on the team, of course. ... He's one of the reasons why I came here."

But for the time being, the Nets are moving forward without him. Nets coach Steve Nash said the team isn't communicating with Irving on his workouts while he's away.

"It's not something we've discussed," Nash said.

Why would the Nets not want him to just play road games?

This is an unprecedented situation as the Nets could potentially go long stretches without being able to work with Irving.

For example, if Irving remains unvaccinated, he'll be with the team for one day (the preseason game Monday in Philadelphia) between Oct. 2 and its opener on Oct. 19 in Milwaukee.

In the second week of the regular season, the Nets begin a six-game homestand in which they will be in New York for 13 consecutive days.

Playing Irving immediately after such long absences from game settings is untenable. And that's just the next month. These awkward starts and stops will repeat themselves throughout the season, and that's less than ideal.

Could Irving be traded?

Despite his All-NBA talent, teams could be reluctant to trade for Irving for several reasons.

There is some question as to whether Irving would immediately report to a new team if he was traded to a city where there wasn't a local vaccine mandate. He has shown a willingness to leave without permission, regardless of consequences. Last season, Irving took an unapproved two-week sabbatical and missed five games for personal reasons, paying nearly $900,000 in fines for violating league protocols.

"Had a lot of family and personal stuff going on," Irving said. "So, just want to leave it at that."

Additionally, Irving has two years, $71 million left on his contract but has a player option next summer that would allow him to become an unrestricted free agent. Teams will be hesitant to give up significant players and draft picks for what could be a short-term arrangement.

Durant, for his part, has continued to say he hopes to have Irving on the team.

What's the impact on Irving's paycheck if he's not playing home games?

The NBA and the National Basketball Players Association agreed to a reduction in pay of 1/91.6 of a player's salary for each game a player misses under the "reasonable cause" portion of the NBA's collective bargaining agreement, a modified formula from the one that each side agreed to for last season's 72-game campaign.

The NBA's expectation, sources said, is that Irving's refusal to get a vaccine shot, and thus being unable to render services to his team, will fall under the "reasonable cause" clause and force him to give up roughly $380,000 per game.

If he misses every game in Brooklyn this season (including preseason games), plus the two regular-season games against the Knicks at Madison Square Garden, it would cost him north of $17 million.

But the players' association, sources said, has stressed it does not believe that is necessarily the case, something executive director Michele Roberts said publicly to the New York Daily News earlier this week.

"They've been reporting that we've agreed that if a player who was not able to play because of his non-vaccination status, they could be docked [pay]," Roberts said. "We did not agree. The league's position is that they can. We'll see."

Friday's Bucks-Nets game marks the first time Irving has missed a game because of the mandate.

Meanwhile, Irving is eligible to sign a four-year, $187 million extension with Brooklyn.

After Durant signed his extension this summer, Nets general manager Sean Marks expressed optimism an agreement could be reached with Irving, but those talks are on ice, sources said.

Are other NBA teams or players affected by local vaccine mandates?

Three cities -- New York, San Francisco and Los Angeles -- have COVID-19 mandates that could affect players on the New York Knicks, Nets, Golden State Warriors, LA Clippers and Los Angeles Lakers.

In New York, to enter any gym -- including Madison Square Garden and Barclays Center -- individuals need proof of at least one COVID-19 shot; in San Francisco, individuals must be fully vaccinated.

While the orders in New York and San Francisco apply to the players on those teams, the situation in Los Angeles is murkier. The Los Angeles ordinance, which was both passed by the Los Angeles City Council and signed by Mayor Eric Garcetti on Wednesday, will go into effect Nov. 29. Starting that day, anyone entering, among other facilities, indoor gyms will have to be fully vaccinated. Staples Center said the Los Angeles ordinance does not apply to it or Microsoft Theater, "who are already subject to an existing LACDPH order addressing this subject matter."

Both the Lakers and Clippers said last month that their teams are, or are in the process of being, fully vaccinated.

Of note, Warriors swingman Andrew Wiggins received a COVID-19 vaccination and will be eligible to play in home games this season, coach Steve Kerr said following practice last Sunday. Wiggins applied to the NBA for a religious exemption, but that was declined by the league.

It's also important to note that "non-resident performers" are exempted from all three orders, meaning that -- as of now -- visiting players are not impacted by any of them.

Who will step up in Irving's place?

The Nets are as well-equipped as any team to handle the absence of a star of Irving's magnitude, with both Harden and Durant available to run the offense. Patty Mills, the team's taxpayer's mid-level exception signing, was projected to come off the bench. Even without Irving, Brooklyn could have the NBA's best offense this season.

"I mean, he's a special player, so it is going to be hard to duplicate what he brings," Durant said of Irving. "But professional sports are about the next-man-up mentality, so we are looking forward to guys stepping up and filling in that role as best as they can."

"He's a special player. We want him a part of this group. But a lot of stuff is out of our control, and we will let him figure that out for himself. It doesn't mean that I will say that I don't want him on the team. He's a huge part of what we do, but guys got to step up in his absence and be who they are and move forward."

When the Nets play in Toronto on Nov. 7, how will Canada's vaccination rules affect Irving?

In an NBA players' association memo shared with players and obtained by ESPN on Wednesday, there is a mention of Canada's Quarantine Act, which allows unvaccinated players to leave their hotels only for official team activities. If those players break the protocols while in Canada, they could be fined up to $750,000 and even face prison time.

ESPN's Brian Windhorst contributed to this report.