Biggest fear... I'll put it this way: that even the modders won't be able to turn this game into a worthy BG2 successor....
I also worry about BG3 turning into some kind of modding hellscape, where I have to download a gang of mods and then apps to install those mods, just to try and stitch together features that could have been realized as part of the base game during EA. The idea of relying on a bunch of loosely affiliated tweaks or ultimate mod pack XYZ, in the immediate afterlife, just isn't something that I relish. I find that once a game is all cracked open like that and I have to define what the gameplay is going to be like from an endless list of mod options at the outset, that I become less invested in the overall experience. Being forced more into the role of ad hoc designer/DM when I'd rather just be a player, if that makes sense. Anytime the response to a given feature request is 'just wait for the modders' I get nervous. I played the vanilla BG games for years and years before ever trying to Mod them, so modding this sequel straight out the Gate just seems kinda weaksauce. I'm sure eventually BG3 will be all dialed, but I don't want to several more years for that to happen, since I've already been waiting a couple decades on this one.