Actually, I like your idea. Only Cruz & Walker have a realistic chance of winning the nomination. After first 3-4 primaries, who ever is leading in delegate count should stay in, and the other given a deal to be on the ticket as VP and drop out.
This will assure Jeb does not win by divide and conquer, similar to 2012, 2008.
I'm not willing to let Iowa, New Hampshire, New York, and Minnesota have that much leverage.