I don't think a lot of people would actually play a bg game for a whole year straight, there's just not that much to do beside the story, unless they want to replay it, but its only for the most dedicated. I'll probably finish my playthrough in a week or so, with all of the side quests done, and jump in to the starfield on release
The thing is you can only see one permutation of the story in one playthrough but there are a lot of permutations...and one playthrough is likely to be over 200 hours. So yeah, I can easily see this game lasting over a year. I'd imagine the minimum number of playthroughs for BG3 to be at least five before moving on from the game. But that's absolute minimum, realistically this will be a 10+ playthrough game.
