What's the driving factor for local stars? I'd think that, as in many industries, big will get bigger. If you become a regional star, you'll probably go multi-regional. I'd be surprised if there'd be any major decline in huge pop stars. Even if they start off indie, one they gain enough traction, they'll be able to out-market others.

There's no reason e.g. YouTube couldn't have music competitions and new huge stars every year.