That is indeed the arc, and the end of it kinda sucks. If you're just going to trap the Ponds back in time anyway, what dramatic purpose does it serve to have them going back and forth about whether or not they want to quit? Their fate pretty much make the conversations in the earlier episodes worthless.
An inescapable fate makes prior conversations about free will worthless? Well, there goes Hamlet. In fact, characters debating big personal issues before having their decisions annihilated by a cruel fate is pretty much what tragedy is all about.