I'm not convinced time was changed at all. Granted they showed stuff out of sequence, but they didn't do the shakey-cam thing they do like when a change to the timeline has occurred. I think time wouldn't let them move on because they already saved Hannah. The future unfolded the way it did contingent upon them traveling back to 2020 to do that, and each time they didn't do that, the-would-be paradox forced them to loop back to the splinter. It's like an anti-paradox; whereas they can't change things in the past without changing the future, this is a time they had to do something in the past in order to make the future play out as it ought to.
Of course if they drop Hannah from here on out and her only real presence on the show was to cure Jones of her depression, then maybe I'm completely wrong about that. But I suspect that she'll play an important role in the series from here on out, unless they kill her off again.