Currently Online 
curl-6 on 26 December 2022
Switch has shown incredible legs, but even the most successful systems slow down eventually, and the Switch is about to turn 6 years old, so it's no surprise it's gradually slowing from a full on sprint to a jog.
I feel like 2023 would be the right time for a successor; this year or sooner would have been premature and a stupid move to cut short such a wildly successful system, but if they wait too long they could risk losing momentum and fumbling the transition.
A 2023 successor with crossgen support for the Switch through 2024 would be the best move in my opinion.
