Maybe, but I know what a Roman denarius is, and that was used 2000 years ago in a region I’ve never lived in.

If even a single full node was still running and a single service was willing to exchange it, you could in fact look up the price. And if digital currencies continue to be a thing (seems likely to me), then exchanging between them may not even require a third party, it will likely be possible to do within the protocols.

Personally I think it’s not an unreasonable question. A bit boring, but I see the appeal.