I don't think this makes much sense. Larian would need to start completely on scratch if they want to do it in a similar manner as BG 3. BG 1 + 2 has a lot of minor NPCs with long background and lore dialogues, such as all the many and various takes on the Iron Crisis in BG 1. Voicing all of that would be an enormous undertaking & cutting it would be a shame. It would require the same effort as making a completely new D&D game - so why not create something new instead of trying to recreate the past?
Also, personally I think BG 1 + 2 are still better games than the still good BG 3, so I don't even believe it would be an improvement. Large parts of this are down to the ruleset.
