Really .. you have NOT heard of this .. I have been talking about it for months.
I am supporting Cruz; but if he were to join with Trump; in a Trump/Cruz partnership, I would be willing to vote for Trump.
And .. there would never be a Cruz/Trump - so I would not worry about that. Cruz would select someone he was confident would be supporting the Cruz agenda, and not someone who had their own agenda.
I think the only way Cruz would take the VP slot is if he got Trump to promise in writing while swearing on a stack of Bibles as high as Trump towers that Cruz could select all appointees to the Supreme Court.