No one single artist could hold back the tide of the arrival of the CD, PC, Internet and MP3. Those all came together and forever changed the face of the music industry. There are too many smart people outside "the box" to ever go back to the glory days of analog and labels controlling everything.
I don't own any Prince albums and never thought he was a megastar, at least not to me.
He was definitely a "megastar" around the time of Purple Rain, then he got "weird" with Around The World In A Day and never truly reached that apex of popularity again, even though I thought those few "weird" post-Purple Rain albums were brilliant, but definitely not albums that those buying Whitney Houston albums by the cases would get. He dropped off from 13 million for Purple Rain in 1984 to 700,000 for Lovesexy in 1988. The bandwagon fans deserted him quickly when they realized he was more about making music for himself than trying to follow Purple Rain.
But IMO If Metallica couldn't "stop the internet", there's no shot in Hell Prince would.