20-Year Prospect
Roller coasters have been around since the 1800s (source).
There's no chance that we'll be without them in the next twenty years. If anything, future roller coasters promise to get bigger and better with each new technological advance (source).
US Thrill Rides, for example, is creating coasters that will go higher than the tallest skyscraper (source).
As real estate comes at an increasing premium, it seems that coasters may be building up instead of out—however 3D coasters that twist and turn in every direction are also getting their fair share of attention.
Hopefully, there will be more coaster production companies instead of fewer. It all depends on how the U.S. economy does in the next couple decades. The good news is, if you have an engineering degree and are trained to build and design coasters, you can also create for equally respectable institutions. Try giving NASA a call.