question Will we run out of new extensions?

You can check which new extensions are live here:
https://namestat.org/

So you see, .love and .art are already live and you can register them, .free is already in status delegated and will be here in future.

Yes, there should be second round of new extensions rollouts in future, so many more will probably come, and there will be definitely no shortage of new extensions, imo

.art is already there.

Epik.com has .art domains at $4.95 for the first year right now.