The player who I would say would be most upset by minutes would be Rozier (also possibly Morris), as they are in a contract year. Rozier comes off a good playoff run and has sights set on a big payday, only to get buried behind Kyrie and probably 4 other guys who should be getting more touches than him.
Add to that the fact that if Kyrie stays (which he announced early on), then he won't want to stay in Boston as a backup. I'll add Brown in the mix too as he will wanting a big year next year, but with Morris and Kyrie/Rozier leaving that will give him back his minutes and shots that were lost to Hayward.