What I find most amazing is the disappearance of .22LR ammo.
9x18 isn't really stocked in large quantities, and almost all of it is imported, except some specialized defensive JHP loadings that some domestic manufacturers have started making. So if stores run out, it takes a while to restock.
Now, if Russia, the Ukraine, and other former EastBloc countries decided to cash in on some of what they've got stockpiled...that could be a bubble, and pop pretty quick.
Other relatively low volume stuff will stay scarce for a while, until the demand for the higher volume stuff slacks off enough. Like .380 back in late 2008-09. If you're an ammo maker, and you can run, say, 5 lines, you're going to run whatever your top 5 calibers are...say, 9x19, .40, .45, .223, and .308. Or maybe no .308 and two lines running 9mm.
And you do that until you get caught up on the high volume stuff, then you worry about lower volume stuff. (I'm borrowing that from Tam at VFTP.)