I disagree with your third point. It's definitely not too late for them to turn Reigns heel. In fact, i think that is going to be their hidden card that they will pull out if they can't get him over at WM.
Oh, I agree its not too late to turn him heel. I was saying I think its too late to put him with a mouthpiece. They're trying to establish him on his own, and having a manager at this point I think takes the spotlight away from him. He's not a big enough star re: Brock, to be able to shine whilst letting Heyman do his talking.
I really think they need to take the training wheels off of him and let him be a little freer, a' la SCSA. You can tell that so many of these young guys, Reigns included, are struggling to just parrot what the writers tell them to say. Take the muzzle off and let him free form a few promos and see what happens.