I can't imagine how much more awkward game development would be without OOP.
Different, but if you design it right, hugely scalable.
Even if you ditched the traditional oop hierarchy and went with a component and entity system it would allow updating of components in a thread which (probably) brings a lot of gains in regards to performance on multi core systems (Maybe not now, but when we get 16 - 32 core systems the advantage will be huge). Of course you get the hell that is designing a decent messaging system so if I was realistic I would say you just exchange one set of problems for another.
Of course when you get down to it and split up entities enough, you basically get something similar to Functional Reactive Programming (which is an amazing concept imho).