Yes, I think you are correct. The winner take all and winner take most formulae begin to predominate now, and Trump looks the strongest in most of those states, at least judging by polls.
The question I don’t know the answer to is this. Assume Rubio and Kasich lose their home states and suspend their campaigns. I don’t know that will happen, but it’s reasonable to assume. Will their supporters go to Cruz or will they split between Cruz/Trump/Abstain. That seems to me the biggest analytical unknown at the moment. Anything other than their going primarily to Cruz means Trump continues to roll. Right?
Yes, the big question is what happens if Kasich and Rubio drop out. I would imagine that a significant percentage of those supporters would gravitte to Cruz, but probably not all. There is the possible phenomenon of bandwagon voting. Still, a big variable.
Polls show that about 75% of Rubio’s voters go to Cruz, some sulk, and maybe 20% go to Trump. ALL the polling I have seen gives Cruz crushing leads over Trump head-to-head, in state after state.