There's truth here.
Going to be honest, the more I think about the finale the more I think it might be more fun for Walker to show up and be an honest to goodness ally for Sam and Bucky, even in spite of their obvious reluctance to accept him. Show him still believing himself to be Cap and genuinely trying to be better. The ambiguity of the character has been the best part about him, and it would be a shame to flush it all and make him a pure antagonist. A broken, failed Cap who is trying to live up to the mantle, and maybe sometimes succeeding due to his values and skills and others failing due to his character flaws and hubris could be a lot more fun.
Though I definitely fall in the camp of those who think watching Sam and Buck thoroughly kick his ass would be a cathartic exercise. I'm just not sure if that's reason enough to suddenly toss aside the delicious complexity of the character they've managed to work with thus far.