So let's game it out...
Most of the pop hits of the last 30 years come from a small handful of songsmiths. Most pop stars already don't really write their own songs, they are more the 'Figurehead' of the whole experience. Their overall look and stage presence are the major selling point (some of them can't really sing without autotune, looking at you Britney).
So a handful of songwriters will be out of work, and nothing much will change. Mayyybe a few artists will sign away their likeness and voice to churn out album after album, hoping the public is none-the-wiser. Pop music may become still more homogenous, since part of the huge pop hits is the unexpected twist worked in that makes it "pop".
It'll be kind of a reverse Hatsune Miku, but things won't change that much. I think the appetite for a completely synthetic pop star is not there in the West - they'll have to be tricked into it. Pop stars are already arguably artificial in some form.