However, the further away people are the more they are going to be affected by the raise in the cost of air travel. And so far it does look like a safe bet that air travel won't become cheaper in the coming years.
Also, at the moment the US Dollar exchange rates work in favour of many foreign visitors. However, that can change. And suddenly a trip to the US will come with an automatic 10% or 25% price increase just because of a change in exchange rate.
Foreign visitors are far from being a safe strategy to rely on.
Give the state of our federal government and their refusal to do anything meaningful to fix the national debt, I'm pretty sure its a safe bet that the dollar isn't going to go flying off the charts in my lifetime... if anything I would be betting it will only get cheaper for foreign visitors.