A Walther PPK could not handle a 9x19 without some design changes due to it's unlocked blowback operation. A modern handgun in 7.62x25 would have to be made on the larger .45ACP/10mm sized frames because it's OAL is too long to fit in a 9mm/.40S&W sized frame.
I'd like to see CZ chamber the CZ-97 in 10mm and also include .40S&W and .357 Sig barrels to be sold as a package. I'd like to see Ruger make the GP-100 as a 5-shot .41 Magnum. I'd like to see someone make a Commander-sized 1911 in 9mm with a correspondingly smaller frame (think a Star BM made of more modern materials). I'd like to see someone besides Beretta make a small-quality auto in .25 ACP. Finally, I'd love to see someone make a carbine in 7.62x25 at a reasonable price.