Yes, but is there a chance that BG3 knows and expects this expectation -- which I'm sure has its own trope in TVTropes and then goes the other way, as in "look, Gale was never a super-powerful demi-god, just a talented dude who spent too much time in the alchemy lab inhaling hallucinogenic fumes, imagined a tryst with Mystra and ended up with a Rincewindnesque black hole of doom in his chest. Now, however, with the tadpole... he might become that and more."
I mean... with the exception of Shadowheart (and only because we don't know anything / she doesn't remember) isn't that the baseline of all the other companions? Wyll was eager but average before his pact, Lae'Zel wants to prove herself but has never done anything worthy yet, and Astarion, well, he was a disaster elf long before he became a vampire spawn. That's part of the fun of interacting with these lovable idiots. If Gale turned out to secretly be a megagod of magic with a super-smart and thoughtful agenda... a part of me would die. BUT I wouldn't say that it wasn't foreshadowed, it's basically a scéne-à-faire for the genre at this point.
