Let's reign in the timescale a little.

All technologies become obsolete and get replaced. Bitcoin is a technology.

Aside from that obsolesce time scale, if ladening Bitcoin with an indebted fiat system doesn't break it, it should last for decades. 

If we try to place the weight of the failing fiat systems on it, it may fail within a few years.

I don't think it will and I hope it doesn't.