What goes into a Nintendo console is not prime silicon. When it's time to design the next console, I am sure Nvidia will still be more than happy to give them a design that they have laying around somewhere in a drawer if it means they ship 100M units.

NVIDIA would still have service contract obligations to fulfil, and would provide support for its existing products for a period of time.

Don’t worry about Nintendo. Their pockets are deep and they are creative enough to pivot. They would retool their stack to support another ARM chip, or another arch entirely.