We'll all be dead when that happens, who cares. Anticipating future problems and thinking ahead is dumb. It's better to just do things blindly without thinking about the consequences.
What's dumb is your post.
If any currency was, by design, to die after some certain time (even 100 years) it would be already reflected in the current price (likely to be close to zero). It could have some value if it had really useful, practical functions, but still would be worthless as a long term investment/store of value.