2. Luke Kornet
Speaking of big men, Luke Kornet might not have that much of a future in Boston either.
Kornet, who signed with the Celtics partway through the 2021-22 season, just hasn't been anything special outside of a backup role. He's played 98 games between the regular season and playoffs since then, averaging 3.2 points, 2.4 rebounds, and 0.5 blocks on 9.6 minutes per outing.
Due to his becoming a free agent next summer, I don't see the Celtics bringing back Kornet for another year.
Sure, he's a solid bench player who can eat center minutes when needed, but that doesn't make him irreplaceable. There's nothing he can do that other centers can't. Chances are Boston management can find a suitable replacement either through the 2024 NBA Draft or free agency.
If he steps up into a bigger role following Robert Williams' departure, Kornet could change my mind regarding his future. At the same time, this is the same player who's started two games since the beginning of the 2020-21 season. If he was capable of handling more minutes, he likely would've proven so already.
I don't think Kornet is an awful player — he has a role on the team and does it well. However, he isn't the type of player who the Celtics would be lost without if they move on after the season.