If White can really shoot the way he has been looking in recent games, that combo would make more sense than Mills/Murray. But I'm not sure that DeJounte really has more upside. People are selling White short in the athletics department. I'm pretty sure his vertical was better than Murray's, and he seems way more coordinated. Murray may well be somewhat more athletic and is certainly longer, but White has above-average size and at least average athleticism for a starting PG in the league. I think his skill-level is already higher than anything Murray can reasonably expect to get, especially on his rookie contract.
There's little doubt in my mind that had LAL drafted White instead of SA, he'd be having a Kumza/Clarkson type of rookie season. For his future, I think White could totally be a starting PG for a team with a star wing like George, Giannis, Simmons or some other big-hands dude whose name I can't remember right now.