20-Year Prospect
Will there be clowns in twenty years? Of course. Will they still be wearing big shoes and white face paint? Good question. The last ten years witnessed a decline in trained, working clowns—from 3,500 down to 2,500—and if that keeps up, Ronald McDonald is going to be a very lonely man come twenty years from now (source).
That said, the spirit of clowns (you know, professional goofballs who get a kick out of making kids laugh) will likely endure. Whether that comes in the form of kids' show characters, iPad apps, or something else entirely is still up in the air. And whether or not today's clowns will be able to find employment in that new field is even more so.
For the next twenty years, you're probably safe, but be ready to adapt to any new clown trends that come our way.