Here's an interesting link to an alternate look at handgun stopping power, FWIW: http://www.buckeyefirearms.org/node/7866
Personally, I think the 9mm is fine and will stick with standard pressure as some others have mentioned. In the past I chose to standardize on 9mm for simplicity since I believe it's as good as any other handgun round and the 9mm is cheaper.
Still, the Great Ammunition Panic of 2012/2013 is a pretty good indicator and there's no reason it can't happen again. I may just buy a 40 or 45 for my next purchase in order to have a good chance to find the ammo next time. FWIW. I'd never sell all my 9mm handgun's, though, and if I had to have only one, that's what I'd have, first and last.