There's not going to be any shortage. There will be a reduction in the availability of experienced pilots, but it will be filled in one fashion or another, just as it always has been. The last real shortage was in the '60s, and UAL responded by hiring private pilots and training them from the ground up, then tossing them into the right seat of a 707 with 200 hours. When the regionals had a shortage a couple of years ago, they responded by going to schools like ATP and working out "pref hiring agreements" that got them freshly minted pilots with as little as 190 hours.
"Just saying 'no'" will get you nowhere except locked out of the process, leaving the ATA and a bunch of politicians to write the rules without your input. Sound like a good idea? You won't like the results. For example, if ALPA hadn't been involved in the drafting of the Age 65 law, retired pilots could have returned with seniority. ALPA's involvement fixed that very quickly. If you lock yourself out of the process by crossing your arms and screaming "NO," then you'll be accomplishing nothing more than allowing a bunch of incompetent fools and corrupt airline managers to decide the fate of your profession. Smart move.