I think the core going forward should be
Brunson, Grimes, IQ, Hart
Think we should keep unless a very good deal presents itself
RJ, Mitch, Hartenstein, Obi, McBride
Happy to move on from
Randle, D.Rose, Fournier,
Fine either way/Bench
D.Jeffries, Sims, Keels
While unlikely - I personally think the simplest move to positively impact the roster would be to trade Randle for Lauri Markanen (and Rudy Gay). Despite Randle being All-NBA 3rd team we'd probably have to add a 1st round pick and/or player to entice Ainge. I would then give RJ this season to see if he sinks or swims when the floor opens up more. Lauri gives you 20-25 and 8 rebounds but most importantly - he can play off Brunson and doesn't seem ego-focused on having to dominate the ball. He can catch and shoot, spaces the floor, and adds length which can always be helpful. Thibs will need to yell at him all year defensively - but not sure his effort won't be worse vs Randle's defensive effort.
Of course we could look into Phx and Ayton - but he's super soft and Mitch dominated him most games they played head to head. Randle on Phx would probably be an ideal fit though... playing 3rd star next to Booker and KD - perfect role!
Draymond Green and Kuminga could be intruiging options to explore as well.
There's always Lavine but suspect it would take Randle and RJ to land him - not sure he's good enough defensively and he has the knee issues.
We could also look toward RJ as the one to move but I maintain that eventually this FO will realize that finding the perfect fits around Randle is not the way to go.