G19 overall width is 1.26 inches, vs the G48 width of 1.10 inches. This doesn't sound like much of a difference, until you are sticking it in a belt.
A while back, I traded a Shield for a M&P9c, with the thinking that for just 0.2 inches wider, I could get almost double the rounds in a package that was otherwise the same size. It was amazing how much harder it is to carry the 9c than a single stack, plus the mags are more difficult to hide. I almost never carry it now, preferring a single stack 9 of about the same size. Plus, I can throw an extra mag in my pocket without looking like I'm happy to see someone.
I consider myself a pretty average concealed carry person who carries regularly. I tend to default to comfort and easy. I say all this to give my prediction that if it is a skinny G19, one of their most popular carry guns now, that this will be the new BIG THING, especially if you live in a state with mag restrictions.