Nintendo Switcheroo

Pem won't buy just 2, he'll buy 10. Especially if it comes with a boxing game.

Nintendo Electric BoogaSwitchaloo!

There are only three likely options
1. Nintendo pulls something out of left field that either still has Switch in the title or doesn't and it's something almost no one predicted.
2. Switch 2: Learning from PlayStation.
3. Super Switch: A tribute to the Super Famicom/SNES and how it succeeded the Famicom/NES.

Switch Extra. Or SEX for short.

Nintendo Switch Series II

NSS2

I think to a minor degree that would have a small negative impact....
also it would leave us all scratching our heads going "Have you learnt nothing from your past?".

I don't see whats wrong with sticking to convention, and doing the obvious thing, and picking a easy to understand, consumer focused name.

Grow the Switch brand, as the core idea, of the switch is still there.
Its a key feature.

Then just toss in a 2, so people that aren't tech savvy all understand its the next in line for the switch.

Time to stop playing silly games with names, to your own detriment.

What if Nin tried to remain creative and do both? Something like:

Switch Too

or 

Switch TU

Nintendo Switch Version 2 (don't actually ever spell out "version" though, just use the short form)

Nintendo Switch V2
NSV2

If by some chance they ended up with a 6th version eventually, they could call it:
Switch VI  (instead of V6)

Not just Switch V though for V5 because that would be too confusing.

Always liked "The Nintendo" as a name for a system that incorporates tech from pretty much every previous system.

I think they will call it Switch UP.

I was about to say ahahah

or Switch U2