i wonder if there can be a time in future when codeforces-atcoder-topcoder and all other ojs would stop making programming contests, because no problemsetter would be able to come up with a new unused idea?

With so many contest happening every week, it makes sense that this must have some kind of upper limit. People can't come up with new problems again and again.

Can someone give some facts which can either prove or disprove it?