Trump would never pick Cruz as his #2. If he did he would be really stupid. Cruz would never be able to get Trump to be #2 even though it would be a winning ticket.
What color is the sky in your universe? That ticket will never happen, and for good reason.
Trump (love him or hate him) is on the level of a Patton. The man has what's called 'command presence', which comes across to one and all.
He's never going to be anyone's #2 at this stage of his life, and at this moment in history. He'll go back to building skyscrapers before stooping to the VP level.
Cruz, on the other hand, will be VP, or he'll have to find some other position in a Trump administration. There is no path forward for him to win the nomination at this time. Perhaps in future, after the American public has become comfortable with him as VP for eight years, but not now. The polling numbers consistently show this to be the truth.
In what world would that be a winning ticket? Cruz has consistently polled in the middle of the pack, despite his excellent conservative bona fides. Ideologically, he's precisely what we Freepers want to see in a president, but he falls short of what most Americans on the right, need and want in a president at this time.
That would be an established outsider like Trump, who also has the command presence and the requisite type of platform to garner a plurality in this primary.
Without Trump in the race, Cruz stands no chance of being part of the Executive branch in 2016. The Republican party establishment would have been able to manipulate their chosen RINO into the nomination, were it not for the entry of Donald Trump.