If pay and conditions improved, this wouldn't even be an issue, high quality people would train as pilots. There is no shortage, there is only a shortage at the price the companies are prepared to pay. Any shortage is entirely of an the airlines own making
I tend to agree with the above however airlines don't really pay any wages! Wages are paid by the passengers and freight owners and the airline has to guess at what the market will stand to cover all expenses and, let's face it, every person has a different perception of this.
Airlines just pass some of the money on as wages after raking off a good amount (some say too much) to cover those expensive executives, new aircraft and other expenses including shareholders dividend.
I see the trouble as airlines and unions not being honest with each other regarding profits and what airlines can afford to pay and what staff really want.