I would think Derick White fits pretty well on a Giannis/Tatum team as a third option connective tissue type PG. He's only a few months older than Giannis so its not like he's off the timeline.
I imagine they just keep him and hope his 3 pointer bounces back.
Absolutely, definitely much better than Gobert. I know a lot of people feel that Giannis won't play center and I think that is why they think BOS needs a center like Gobert. I think these modern day teams don't necessarily have a Center. What is a Center anyway these days? In my view, any team needs some rim protection, rebounding, maybe someone that can catch and slam a lob. Giannis can do all of this whether he is called a center or a PF or a big. And you want every player on the floor to present some level of offensive threat. Giannis has that too.
One of the reasons that BOS can "get away with" playing Giannis at Center is that Tatum rebounds so well. BOS doesn't need a guy like Gobert if Tatum and Giannis are on the floor. Plenty of defense. Plenty of rebounding. Giannis cannot hit the 3 enough to impact defenses. But he can dribble right by most traditional bigs, forcing rotations, creating space for shooters, and so on.
I think White - Tatum - Giannis is a very formidable trio. Better than White - Brown - Tatum.