At this point the Switch pro is probably a long way off, if it is still coming.
References to the new 16nm X1 die shrink 'Mariko' (chip used in the Lite and likely in the new Switch revision coming up) have been first found in the Switches OS over a year ago.
If there was yet another different chip coming up, presumably we would see hints toward it in the OS already.
There's probably going to be a silent revision on the standart Switch later this year, with the new internals but no further changes. They might not even allow developers to leverage the additional power in the chip (it's theoretically up to ~30% faster than the Switches current highest clock) to keep up parity with the OG model, so the main improvement would be battery life.
So I expect as silent revision, featuring better battery life sometime this year, and sadly don't really see a true 'pro' on the horizon. At this point I think a fully fledged Switch 2 might be more likely, with maybe a customized, die shrunk X2-based chip in it.
Porting to 12nm (As it's based on 16nm FF which in turn is based on 20nm Planar) is a fairly straight forward task, so there is room for improvement in a few years time still.