I think a Glock with the 19/23/32 frame size, but thinner, would be a great seller. How much would you care to wager that Herr Gaston's design engineers could figure out a way to fit nine, or maybe in the legal limit ten cartridges of 9mm in a pistol that size? How much are Glock HiCaps going for these days? Are they going to get cheaper? If all you can get are 10 round mags for a 19 or 23, why wouldn't you want a slimmer pistol that holds the same number of cartridges. A decade or so ago, this was less of a consideration. But with the '90s proliferation of states allowing concealed carry, this is one of the key advantages of a pistol like the Glock.
As for the vagaries of the importation laws and GCA '68, Glock managed to get the 26/27/32 in the country, didn't they?
Moreover, I would probably buy a full sized Glock 9mm that was single stack, or pseudo single stack. Glock could definitely manage to get ten 9 mm cartridges in a slimline fullsized 9. I think it would make for a very secure grip on the pistol, and would be easier to conceal with certain types of carry, with IWB immediately coming to mind.
Bring 'em on. I'll buy 'em!