If this is true, this would be the first-time since the NES/Super NES (and even some overlap with Game Boy) that cross-gen Nintendo games were common. But in all fairness, I think most of those games (if not all of them) back in the day were puzzle games. They don't exactly require sophisticated specs.
As for possible cross-gen Nintendo games...
-Mario Kart 9: This is a no-brainer. Mario Kart 8 Deluxe has brought the series to financial heights and a level of content never seen until now. With how many Switch players are out there, making 9 a cross-gen game to get it to as many Nintendo players as possible seems like a great financial boost.
-Metroid Prime 4: Prime 4 has been in development for a long-time. It's been designed with the Switch in mind, but there's no reason it can't be cross-gen.
-2D Mario
-Wind Waker HD and Twilight Princess HD
-Rhythm Heaven
-F-Zero GX HD
-Star Fox
-Donkey Kong
Lifetime Sales Predictions
Switch: 151 million (was 73, then 96, then 113 million, then 125 million, then 144 million)
PS5: 115 million (was 105 million) Xbox Series S/X: 57 million (was 60 million, then 67 million)
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima