As far as under 30 goes, who wouldn't championship teams potentially want?
PG: Murray (not there yet, but his shooting is improving unlike someone in Philly)/Tre (he was a rookie with little minutes but his skillset has upside as a backup PG)
SG: White (he just needs to be healthy consistently tbh)/Walker (the upside is there but he's definitely a question mark)
SF: Vassell (really good 3&D prospect just hasn't gotten consistent minutes yet bc he was a rookie)
PF: Keldon (the 3 point shot is getting better, big and strong, bullies opposing players. You see how he's doing with the Olympic team early on)/Luka (prototypical what you want at the 4 we just have to see how he develops)
C: Poeltl (I guess you could argue he's not a starter on a championship team bc he can't shoot, but I definitely think he could play a big role on one.)
Most of these guys are a good bit younger though. When you're 28/29 you know what you have in a player. 23/24 not so much always.