I’ve been saying for weeks that Cruz’s best chances are that it become a 2-man race ASAP, or that Trump finally lets his mouth go too far for even just a modest chunk of his celebrity-worship followers. As more candidates have dropped, I believe that those votes have eventually settled on Cruz. The NBC poll seems to confirm my suspicion. I hope that is the case. Of course I may be wrong (something that Trumpeters cannot ever admit for themselves).
The assumption Cruz will get support from those that drop out is tenuous at best. First of all, if one is in favor of Cruz's "style", they are free to support him now. Second, if you look a the Libertarians whose candidate has left, you'll see Trump has gotten the vast majority of that support.