We’ll all be voting for VP Robot in November as the GOP-mandated bail-in behind President Trump ... so it can wait until then.
With Trump, Rubio, and Cruz in the race until the end, we're likely to get a brokered convention with superdelegates making the final call. If Trump has a plurality, he'll need to make some concession to the establishment for their support, which may very well mean picking Wind-Up Toy Rubio as VP. Even without a brokered convention, he may do it in order to win over pro-establishment voters in the general election, kind of like Reagan's concession to the Rockefeller Republican wing of the party when he picked George H.W. Bush as his running mate.