Probably we won't be seeing a shortage of licensed pilots within the next few years. BUT what some airlines are already seeing now is a almost threatning shortage of qualified candidates.
Take the situation in Germany. On the one side pilot schools are churning out record numbers of new pilots, must of them headed directly for unemployment. On the other side Lufthansa is not able to fill its annual demand from the school at Bremen. The school has the capacity to train sufficient numbers of people. But classes even had to be cancelled due to the lack of students. Why? The number of applicants for the initial screening has been dropping lightly over the last few years, but the number of those making it through the screening has dropped dramatically. As someone already mentioned, aviation careers aren't desirable anymore,leading to lack of interest from the young generation. Blame it mostly on short termed greed commonly known as shareholder value, bloating the importance of quarterly profits over long term profitability.
Other airlines are starting to get into the same problems of not being able to attract sufficiently qualified candidates, some are still ignoring it due to a current (short termed) overstaffing, others are already hurting their business opportunities due to capacity constraints. With congestion in the skies due to grow again, demands on qualification will rise, due to the pressure to keep quality (SAFETY) at the same overall numbers (actually it will be increasing with the number of movements going up). The current scheme of private enterprises (pilot schools) luring aspirants into a financial desaster without telling them the truth about their future chances will eventually kill the industry. IMHO we will be seeing the rebirth of sponsorship schemes, as bean counters will sooner or later figure out that a reasonable investment into the future will help keep future costs and losses due to public safety perception low. It all comes down to how much does a hull loss cost and how many can I afford before it affects my balance sheet.