There's been speculation since the Switch launched and soon we'll get to see whether Nintendo still makes dedicated handhelds/home consoles.
If the Switch Pro can't (easily) be used as a HH then it's fair to consider it a home console, likewise if the Switch Lite can't connect to the TV then it's surely a handheld.
So, place your bets.
Will the new models of Switch be able to switch?
My answer is yes.
The dock/battery might be an accessory but any new Switch model will be capable of playing in HH or home console mode. At worst, it might mean that home-console mode doesnt see a power increase and the handheld model might need an extra large battery pack to truly be considered portable but regardless, the Switch will continue to switch.
Don't Play Stationary 4 ever. Switch!