I know there are people saying there is a chance BG3 will look like that (how are the graphics?), an ARPG... but I have doubts that any studio would opt for such a drastic departure from the previous games.
It is, but Dragon Age: Oranges and the Mass Effects (I think... it's been a while) worked in the same way with multiple party members. Sometimes it was fun in Oranges to guide my party around by controlling Dave, my imaginatively-named mabari.
As for departures, Larian have already done that extensively with the Divinity series, which has gone from fixed-perspective isometric real-time to third-person real-time to tactical to variable perspective isometric turn-based, so I certainly won't be making any bets.