Baldurs Gate is a DnD story. Larian made clear the mechanics are based on the 5e ruleset, the most popular version of the rulesets that exist.
Isn't 3.5e still more popular than 5e?
5E is massively
popular, thanks in no small part to the huge boom in Actual Play podcasts and shows. Just take a look at the game listings on a site like Roll20.
Anyway, back to OP. This isn't Larian's first rodeo. I do hope they change their minds about a few design choices I personally disagree with, like party size, and I hope they take a few ideas from the feedback that they may not have considered. But they've definitely got an excellent game at its core, and I think they realize that--and they aren't going to radically change direction when that distinct Larian style is what got them this gig in the first place.