They’re fucking Nintendo. They made the consoles they’re showing off in their museum. They absolutely have the ability to supply that museum with equipment and maintain it in perpetuity, because they fucking invented it
That’s not the point of it though. Not about whether you could fix or maintain it when operating it, it’s about not operating it if presents a notable risk of failure. The Smithsonian doesn’t start grinding cornmeal in a bowl from the Mississippians. The Connecticut Museum doesn’t take it’s colt rifles out the range for target practice. These organizations would use a replica to demonstrate what it was like, as opposed to risking damaging an original article.
Thats also not even necessary true either. While they may have invented there various consoles, at some point it will be nearly impossible to acquire replacement parts. They don’t manufacture the ICs or mainboards or the various discreet components. So if there’s no old stock, how would they “fix” a broken N64 (or later) console? It might be theoretically possible to fab a NEC VR4300 to replace a dead one, but probably cost hundreds of thousands, and it wouldn’t be broken anyway if you hadn’t left if running 16 hours a day so some sweaty tourists could play on real hardware.
And why would they? It would cost more, be more work, and have less reliable results than using a completely replacable computer running an emulator. The entire consumer facing side of the equation is worse if they run the games on the actual hardware, as long as the consumer doesn’t see it, which is really down to how they design the exhibit.
Do you think the public is understanding enough to accept that “The NES is really old and it broke so you can’t play super mario bros today”, when it’s the only day you are gonna be there? Temper tantrum, bad reviews, loss of face. From what I understand, Japan actually cares about all that, so Nintendo probably does as well.
They could replace all the parts in a SNES or NES with components indefinitely, because inside are either off the shelf components or specifically made components made after schematics from Nintendo. So even if nobody makes such parts anymore at the moment there is nothing (but time and money) that would stop Nintendo to order new parts based on their schematics.
Most issues with old consoles can even be fixed by hobbyists and if they can’t that’s because they don’t have access to the needed information to create new versions of the tailor made components.
So there should be no issue for Nintendo to supply their museum with replicas forever. Yes it would cost way more money then using Emulators, but it would be way more appropriate for their own museum. But no they have chosen the lazy route.
