If Trump were replaced by Pence, I think there would be a noticeable difference. The agenda, though perhaps similar, wouldn't be identical, and their personas are significantly different.

Just as an exercise, if Pence were president and Trump were VP, do you think we would be hearing as little from Trump as we're currently from Pence? And before you say, well, Pence is the VP, you're right, but I can't imagine Trump taking second seat to anybody, while Pence has.