A lot of people have been saying that Jaime’s arc is one of identity, not redemption, but couldn’t one lead to the other? I imagine that his run-in with Stoneheart will force him to confront the aspects of himself that he’s been running from, and if he’s able to accept the reality of what he’s done, couldn’t that be the “rock bottom” for him to finally start redeeming himself from?

I suppose it depends what you mean by redemption. I don’t think Jaime’s getting a happy ending where he becomes a better person and lives a good life. 

I think his run-in ends with Brienne dying to save him, then coming back to find that Cersei is responsible for the death of their last child and has/is going to use wildfire on King’s Landing, making his dishonor worthless, and then is going to murder her and commit suicide. 

To me, that’s a tragic arc, not a redemption arc.