Increasingly there is a sense that Pence does not help Trump in his run for reelection in 2020. He was brought on to help secure the evangelical vote but evangelicals have been very loyal to Trump and would likely not abandon him even if Pence wasn’t on the ticket.
There are rumors of replacing him with others such as Nikki Haley who could shore up the GOP women vote. Replacing the Veep seemed pretty far fetched until seeing the Trump/Pelosi/Schumer brawl yesterday. Pence looked very very uncomfortable and strangely frozen.