It might be better to ask BTCBTCBTC $$$ which ends first. The collapse of US$ could be devastating and obviously domino effect of failures into other part of civilization. It would last as long as we live if not replaced by other (cryton)currency(s) as reserve currency.

Yes.  The collapse of the US dollar would inevitably lead to worldwide economic detestation, as it is the reserve currency. It certainly isn't happening within 8 years.  If it does, I don't want to be on this planet because some seriously fucked up shit is probably going down, and it may very well have to do with a nuclear winter or natural disaster on a scale like we've never, ever seen before and wouldn't see again for millions upon millions of years. 

Get real!