Does he? I'm not familiar enough on how most delegates are chosen but you don't think when they get released they'll coalesce around Cruz or Kasich?
That's the million dollar question. Unless Kasich goes on a serious winning streak, if the 8-state rule remains in effect, they can't rally around him. I suppose they could interpret that rule to say "on the first ballot" the candidate needs a majority of delegates from 8 states, but that would be a bit of a stretch.
As noted often, Cruz has not been well-liked by the GOPe (that's an understatement), and the contempt is generally mutual. So, for a Cruz-supporting-rally to occur, noseplugs will be de rigeur for all participants.
Any slight change to the rules - or Trump-disapproved interpretation - will get branded by Trump as evil and evidence that he should win. I'm not sure if he just doesn't understand the rules or intentionally is misrepresenting them. If he doesn't hit 1,237, then delegates get to decide regardless of how many states he's won.