I honestly feel that the firearms market has pretty well stagnated at this point, hence why even when a new cartridge is introduced with an actual tangible benefit or compelling features, it goes largely overlooked.
For example, consider the .357 SIG, a cartridge designed to duplicate the performance of a .357 Magnum FBI Load out of a 4" Barrel. It was relatively powerful, penetrated hard barriers like autoglass while maintaining a flat trajectory with enough energy to reach vitals, and could fit in the same size frame as the popular 9mm/.40 firearms of the time, yet only a few police departments adopted it, so it never really caught on and has since faded into relative obscurity. (Last I heard, SIG stopped chambering the P320 in .357 SIG.)
Another example would be .458 SOCCOM in Rifles, a cartridge designed to duplicate the performance of a modest .45-70 load out of a standard AR-15 Pattern Rifle, using standard, unmodified AR-15 Magazines. It's one of the most powerful cartridges you could possibly fire out of an AR-15, yet it never really caught on, always overshadowed by otherwise gimmicky AR cartridges which only featured a minor increase in performance if any, with some benefit which was only situationally useful for specific builds like higher velocity out of shorter barrels or better accuracy.
Of course, there are many other examples of cartridges with otherwise compelling, entirely tangible benefits, yet they were completely overlooked. So it's really not surprising that .30 Super Carry didn't catch on either when it really didn't have much at all going for it besides marginally higher magazine capacity in 9mm sized pistols.
It honestly seems like the only way to make a splash in the civilian firearms market is to first score a major government contract which in turn becomes widely adopted by law enforcement agencies across the country, since civilians mostly turn to law enforcement for an example of what they would be best suited to carry, ergo cartridges like .30 Super Carry which were designed to appeal towards the civilian concealed carry market don't stand a chance.
Granted, since there's clearly a demand for it, if .30 Super Carry could somehow be finangled into a smaller frame pistol comparable to that of .380 Pocket Pistols, then it could sell, but seeing as it was clearly never designed with Pocket Pistols in mind, that's pretty well impossible. Perhaps if it were shortened, downloaded to less extreme pressures, and rebranded as ".30 Micro Carry" then it might be more compelling, but that would come at the expense of being comparable to 9mm in power, thus likely making it too similar to .380 ACP.
Still, I think that it would be possible to accommodate .30 Super Carry in an intermediate frame size between a Pocket Pistol like the Ruger LCP and a Micro Compact like the SIG P365, or perhaps just a beefed up, Ruger LCP, but then it would likely inherit the same degree of limited longevity which many of the popular Pocket Pistols such as the LCP are known and ridiculed for.
Unfortunately, there's just no such thing as a free lunch in that regard. You can either have a durable pistol that can hold up to a lifetime of weekend shooting, or you can have a featherweight pistol that can be comfortably carried 24/7.