I mean, the C's went 16-3 in the postseason with KP only playing like 7 games (and 4 of them were either in limited roles or the game he got hurt against Miami).
I'm not gonna worry about the beginning of the season. What really matters is health in April and beyond. I expect them to keep 1 of Tillman/Kornet, and even someone like Kornet can bridge the gap in the regular season. If they need a little more, CBS can deal a few 2nd rounders at the deadline again.
I do think the Celtics are hoping Queta can take a similar step as Hauser. A full offseason of work and gaining more experience early next year in hopes he can carve out a decent bench role. Springer/Walsh feel two years away, but Queta could find a slightly bigger role next season IMO. Tillman as well if they keep him.