The problem is that high clock speeds cost heat and energy consumption. So it is possible to solve this problem by finding a new material for making processors. Its only a matter of time until someone figures it out. I read an article 2 years ago about using diamonds in chips, to solve exactly the heat problem, the problem was that it was going too be expensive, so maybe if someone thins of a cheap alternative to diamonds we can have some very good results. This may take a year or 10 years, i don't know if its even going to happen, but until then multi core CPUs are a good alternative.