All regions: No, definitely not.

2-3 regions geographically close to one another: that's basically SWSH and ScaVio.

A new region based somewhere else in the US where you're able to visit Unova and/or Orre.

Or an Ireland region where you visit Galar.

But it'll never happen.

https://x.com/GardeningAdam/status/1813149133693239729?s=09