Of course, that's a distinct possibility.
Still, the option to have a kitted class, which I can multiclass with another kitted class, while definitely opening up loads of possible (and quite probable) room for OP builds, somehow still makes me giddy for the entire thing, in a way that's very similar to how BG2's kit system made me feel. And that's a feeling very few games today can elicit in me.
Whether we can make OP combinations is a "wait-and-see" thing. I don't actually want that, but ok. What I wanted to say, however, is that the OP combinations in BG are very rarely ones that don't include OP classes. Mage/Thief, Kensai/Mage, Berserker/Mage, Fighter/Mage/Thief, etc. all include, surprise, surprise, mages. The only OP combination I can think of that doesn't include mages in some way is Ranger/Cleric (and you have to be of good alignment, which is gross). So, yeah.