I think they should add characters to the cinematic universe outside of the Avengers. Gives it the feeling of an actual universe, instead of a bunch of tie-ins orbiting the Avengers movies. Daredevil is a great character to start on, so reverting the rights to Marvel is probably the best call. As for the story, I agree with the consensus going around that it should be based on Born Again (there's even an appearance by Cap, Iron Man, and Thor, so we've got the cameo done right there). Actually, you could do a pretty close interpretation of Born Again and it would work. Just replace Nuke with Gladiator.