I have been thinking that as well
I don’t see Trump doing two full terms, I think he would want to get back to business or enjoy his children and grand children
Also, if Trump fixes trade, immigrations and brought back the Economy, he would have done what he promised, if he can do it in four years, why bother going for another 4? Leave on a high note.....
I favor Cruz but will certainly support Trump in the finals if Cruz accepts the VPOTUS nomination and especially if Trump agrees to defer to Cruz on judicial nominations. Cruz could bring a LOT to the vetting of judges and SCOTUS justices. If Trump used Cruz as a sort of Chief of Staff and close collaborator, the two of them could achieve a monumental restoration of this republic and, as Trump says: Make America Great Again!