Delegates elected by the voters at local and state party caucuses (not GOPe) are the ones who’d have to find a solution at the convention if neither Trump nor Cruz has the requisite number of delegates. That’s the purpose of a convention.
So put yourself in those shoes. You’re an elected Trump delegate from your state. Trump doesn’t have the numbers to win on the first ballot. What do you do?
Vote For Romeny!
Why would I change? If I'm a representative for voters, would I not need some assent from them as to whether I change my vote?
Otherwise, the game is rigged, but we knew that already.