It is interesting to note that by convention time Cruz will have probably won at least 8 states and qualify under rule 40.
So by that time it would be between Trump and Cruz if neither had won it outright.
The Cruzites just can’t see that changing the rules says neither Trump non Cruz is going to get the nomination.
Cruz has already won 8: Iowa, Alaska, Oklahoma, Texas, Kansas, Main, Idaho and Utah.
The only candidates who qualify under Rule 40 are Trump and Cruz. Unless Kasich suddenly wins 7 more states, Trump and Cruz will be the only ones eligible when the convention starts.
The only way I see the convention adopting a different rule is if all or most of Trump's or Cruz's delegates join with the delegates pledged to the ineligible candidates to do so. Since the rules are adopted as the first order of business, it would be pretty stupid for either Trump's or Cruz's delegates to open the door to additional nominees.