I think he's peaked. He's not winning new supporters. If you're not Trump now, you're never going to be. I think his only shot to go into the convention with the most delegates is if it stays a three-way race the whole way and he's the first of three. I don't see him ever getting to 50%+ support, and there's no chance he comes out of a brokered convention with the nomination.
I roughly figure Cruz will get the Carson, Paul, and Santorum voters. Rubio gets Bush, Fiorina, Kasich, Huckabee, and Christie. Projecting that onto the Iowa results gives you 43% Cruz, 24% Trump, and 33% Rubio. That shifts to Rubio and Trump in the bluer states, which leaves a very tight race.
Good post. Hard to say if he's peaked yet, but I agree he never makes it to 50% of republican support. His biggest advantage has always been that there were so many candidates peeling off voters and spreading the support out. Egos of the "lesser" candidates will be key to how long this Trump shit show plays out, IMO. How long until Bush, Christie, Fiorina and Kasich finally accept that they are not going to win and step asside for the good of the party?
Bush has the money to go all the way to the convention, but he dies a little more as a legitimate political figure with each passing day, so its hard to say what his pain tolerence will be going forward. I'd think that the writing on the wall is pretty clear with Fiorina, but I can't belive someone with her drawbacks would have run in the first place, and I don't know how well financed she is so it'll be interesting to see how long her charade lasts. Kasich, IMO, remains the most sensible candidate, and I suspect he won't go past NH before he comes to terms with the fact that he is getting no traction. I think Christie won't back out until he absolutely has no other choice, and he'll keep dividing the "establishment" vote through the Super Tuesday primaries.
Supporters of any of those folks will more than likely not be going Trump's way, as all of them have pitched themselves as the anti-Trump to one degree or another in the race so far. I'm not as convinced by Rubio's third place finish in Iowa that he's going to keep making strides -- especially when Trump starts to focus on him more with attacks. It will be interesting to see where the support of those who drop out will fall.
I think you are dead on about Trump not making it if there is a brokered convention. I would think that the same would be true of Cruz, which would seem, at the moment, to indicate that it may be Rubio by default. That, IMO, is the best hope, but that is certainly far from a sure thing at this point.