My guess is, Trump's ego won't let him run with anybody who isn't completely colorless and easily led. Mike Pence certainly fills that bill. He has -- had -- excellent conservative credentials, and then turned out to be easily cowed as Governor by various opposition pressure groups.
So, Pence won't hurt Trump's chances, or upstage him. Trump's on his own, which is where he wants to be. For Indiana, Pence's moving up means someone else will run for Governor, and the chances of the GOP retaining the Governor's seat in Indiana just went up a notch.