At the end of the day, there are so many factors that no-one can say for sure.
If we're all still here in 2018 I believe in all likelyhood the dollar would have combined with other currencies, much like the euro has done.
As for the concepts of a cheaper dollar, it certainly helps with exports, which in turn can help sustain unemployment considering the necessity for an increase in output, which usually assists the manufacturing industry. But don't for one second think that this is an entirely good thing.
Most of our cheap, manufactured products are produced in places like China or Mexico. A decrease in the value of the dollar makes all of those porducts more expensive. Add to that an increase in oil prices and so an ultimate increase in delivery charges. Our morons in charge of running the country and through pressure from interest groups, wish to seek alternate sources of energy like ethanol from corn. Aside from it being entirely inefficient, if the price of corn goes up as a result, the price of most drinks and a ton of foods will again rise - go and look at the amount of corn syrup found in our products. In other words, major inflation.
The US market is different from many, as it relies on us, the consumer. They drop interest rates, not to simply put more money in the system, but to try and maintain consumer confidence. If consumer confidence is high then spending continues. Problem is, conusmer spending continues, but does so on credit. Furthermore every time we borrow more money from the fed, we do so at interest - so the debt continues to grow. Who knows how long this will be sustainable.
Also, a decrease in the value of the dollar means a lessening of imports, which means an increase in unemployment in that sector.
At the end of the day, it is a balancing act, but right now it seems to be heading towards inflation as well as the recession. Having said that, we've been in recession for some time, it's just that the figures they give you on TV are misrepresentative as they do not account for the rise in oil prices or food. Add all of that in and inflation sits over 11% at the moment.
But there's more. The world trading standard is in US$. If we continue the path we're going on and the dollar maintains its devaluation, there is always the possibility that we loose our right to print money and the trading standard changes - more than likely to be the euro. Not to get into the debate about the war on terror, but if you really want to know why our leaders hate the Iranians so much (and Venezula for that matter), it's because they are pushing to drop the dollar as the value for oil, and move to the euro. That's 40% of OPECs oil!
There are a lot of 'ifs', but based on our current leaders view of what's improtant in the world, the dollar will likely continue it's decline. Interest rates can't go down much more, and when that stops, so the trading in Wall Street will begin to slow. That's when consumer confidence will get destroyed, because so many people think the stock exchange is a good place to invest money - bad choice. If you have extra cash, do it for fun. If it's your life savings... very risky.
That's why I feel it's likely that the dollar will combine with other currencies - hopefully not, but very possibly.