Skyrim is sitting at 42 million sold. BG3 won't come anywhere near that. I am skeptical it can reach the more than 10 million in sales for DA:I..
Skyrim is not a CRPG, nor DA:I. And you are ignoring that BG3 is on EA, din't released yet, and that this games are available on consoles.
Only on steamcharts, they put BG3 on 1m to 2m users.
edit : on steamcharts, DA:I which was recently released to steam is on 20,000 .. 50,000, a tiny fraction of other EA franchises, like BF1 with 10x more users.
