$400 USD would be the sweet spot for price I feel; higher than that and it starts to get a bit pricey for low income buyers, while any less doesn't seem feasible given inflation and the fact Nintendo always sell hardware at a profit. It would still sell at $450-500, just not as much.
A $400 Switch 2 with a packed first year including Mario Kart 9 would sell basically whatever Nintendo can ship for its first year.