Never played the Souls series; vaguely interested, but I suspect I'd just get pwned considering I am not good at combat and slow to figure out even fairly rudimentary tactics.
I think for me, what I'd like to see with BG3 is for it to be moddable, so I can add or change stuff as I see fit. I would expect (perhaps naïvely) that it'll be similar to the Original Sins in that regard, so we should see a toolset sooner or later but will also see the rather modder-unfriendly Granny format too, though if it catches Norbyte's interest he'll likely update his extraction/conversion tool to do its thing.
It's running on the same engine, I doubt that it's a big investment to make it modable and general trend is "modable is free content" and Larian have been very consumer friendly so far.