The one thing this election has all but confirmed for me is that over half of the country supports these things unabashedly, and I highly doubt porn will be the hero that magically changes these people. It's already banned in multiple conservative states, and all of them just voted red again.
Honestly, I believe that if the Trump admin brought back prohibition, his bootlickers would be the first in line telling us how it's the best idea ever.
He wouldn't do it. There's too much money being made there to already wealthy people that support him. I could see him threatening and blackmailing to get a piece of the pie though.