When the greatest defensive player of the generation says he wants certain guys to stay, and even tries to throw a bit of a threat behind it, the Rams need to pay attention (and they are, no doubt).
I really do doubt, however, that if one or the other of OBJ and Miller aren't resigned or even both, that AD is gone. That said, I don't think the Rams gave up 2 high draft picks for Miller for a half-season rental. And the OBJ thing is actually going to be pretty easy to deal with, likely. His injury keeps him with the Rams on the cheap.
Likely the Rams will let Miller test the FA market and come back to them with the offers. The Rams are known to do that to be fair to all sides. But.... it won't escape teams that Miller is on the back side of his career. Will someone devote a huge cap number for him? And, besides, he really only works well as an OLB in a Fangio type system. That, too, limits the options. He's not a hand in the dirt guy.
AD has clearly bonded with Miller and OBJ. Miller and OBJ make the Rams better. I have no doubt that the Rams will find a way to keep both. They seem to work a lot of magic with that cap when no one else thinks they can.