a high capacity 5.7x28 subcompact pistol?
5.7x28 is about 40mm overall and right at 8mm in diameter. So, it's right at 10mm longer and only 1mm smaller diameter than 9x19. The need to cant the rounds to reduce the magazine length offsets the skinnier rounds. Otherwise the beast gets to Wildey dimensions quickly--pretty much the opposite of "sub compact" sadly.
Might be easier, actually, to make a subcompact in 7.62x25--but it would have a very fat grip
Didn't compare it to a Savage. Did notice the rounds stack similarly to those in my Walther P22.
There's only a limited number of geometries for building a double-stack single feed magazine.
There's considerable engineering in the humble box magazine.
How much "straight" (e.g. single stack) is in the magazine affects how easy/hard the magazine is to load. It also affects follower design, too.
Now, the engineering answer would be to use a double-stack double-feed magazine--but, that introduces extra width in the slide/bolt to accommodate the double-feeding. This is often seen as counter-productive in a "concealment" pistol.
Most of the people in the micro-compact market are basically committing their purchasers to getting some sort of loader to get 10 round into the space of 8; or 12 into the space of 10; and so on.
Now, where will the future go?
No telling.
Laugo has found a new way to lock up a pistol--whether the market (and time) decides it's too complicated (versus Browning tipping barrel) only time will tell.
Maybe we will see developments in gas-delayed blowback; or maybe flapper-delayed--both are simpler ways than just relying on mass in larger-caliber fixed-barrel pistols.
Maybe not.
Maybe it's phased plasma pistols in the 4 watt range.