Appearing on FS1's The Herd, Fox Sports reporter Chris Broussard said there is at least some talk within the organization that Irving may not be back (starting at the 3:55 mark):
"I will say this: There is some sentiment within the Celtics organization—let's see what happens with the second opinion—that possibly, this is far from definite and I don't want to sound the alarm, but possibly, this could put his season in jeopardy. If that's the case, then [general manager] Danny Ainge is looking more at, 'You know what, if it's the case, we'll rest him now.' Don't push him through this season just to have him play in the playoffs when the knee's not really right. Let's get him healthy, and then he and [Gordon] Hayward come back next season. Now, I'm not saying that’s gonna happen. I'm just saying there is some thinking that let's see what happens with this."
Irving has missed Boston's past four games, and the Celtics have gone 2-2 during that span.
Boston is considered a serious championship contender this season, as it sits second in the Eastern Conference at 48-23.
Irving has been the driving force behind the Celtics' success, as he is averaging 24.4 points, 5.1 assists and 3.8 rebounds per game.
Without Irving or Hayward in the lineup, the Celtics lack a true go-to guy on the offensive end.
Both second-year man Jaylen Brown and rookie Jayson Tatum are talented scorers, but they aren't yet at a place in their respective careers where they can be expected to regularly take over games.
Also, Boston is lacking in terms of backcourt depth since Marcus Smart is also out, which places additional pressure on Brown and Terry Rozier.
The Celtics have given no indication that Irving won't be back this season, but he is expected to miss the team's upcoming four-game road trip, and he is set to get a second opinion on his ailing left knee.
If Irving is unable to come back this season, it opens the door for the first-place Toronto Raptors to reach the NBA Finals for the first time, or for the LeBron James-led Cleveland Cavaliers to reclaim their place atop the Eastern Conference.