Already happened (in multiple ways) with Tupac. Released posthumous albums and reproduced his likeness holographically. I think its inevitable that actors will do the same.
It's not such a big difference between watching at home a concert, and going to a fake concert. Both are not connecting you to the artist, just giving you their music and performance. Arguably it's much more impressive if you go to the holographic concert - you have a bunch of vibing people to mingle, impressive sound systems and fancy visuals all around.
