Chinese Yuan.
They will be forced to evaluate numerous times in coming years.
Of course opening an acct, or trading it could be a challenge.
Pound? Many people say this because they just raised rates outta the blue, but when cable is near $2.00 its a struggle. Long term I see US i rates at least equal to theirs.
Loonie? Only if you think the oil/commodity play has legs. They've had great numbers last few years, but its almost entirely due to commodity prices/exports (same with Brazil). Canada is basically a very educated third world country as a major portion of GDP is from raw materials.
If you aren't planning on travel abroad, I wouldn't worry a whole lot. In the short term, dollar denominated investments could get hammered, but in the long term, it could turn on a dime given any of a number of scenarios. Maybe just diversify LT funds a little, and focus on trading profits?
Just my 2 cents.