I have this crazy wish that a company would come out with a 9mm about the size of a Glock 42 in 9mm -P (yes, MINUS P) basically just a 9mm with a 100 grain bullet or less held to 25,000 PSI max, but capable of shooting some standard pressure 9mm, but with a big huge warning that says "NEVER SHOOT ANY 9mm +P in this firearm" on the slide.
My thinking is one could still have a small gun that shoots slightly more powerful ammo than .380 and be able to shoot a few boxes of standard pressure 9mm just in case they need to.
You could get a Lone Wolf 9mm Makarov barrel for the Glock G42.