To hedge or not to hedge? (US$ going "bankrupt"?)

A lot has been said about using currency hedged ETFs or not (for example the canadian XSP from iShares Canada which is hedged but has a higher MER than the american unhedged IVV - chosen by Canadian Capitalist).

My personal choice is to pay the extra MER which basically equates paying an insurance against currency fluctuations. Using an ETF to do that still results in much lower MERs than typical mutual funds.

Yes, currency fluctuations even out historically, but what if the situation is bad when you retire and you need the money? Worse: what if the US dollar sinks for the next 50 years? Although very unlikely, that could happen if they keep spending hundreds of billions every year on wars for example ...