Glock guy at the range today with a table of guns. Played with the cutaway, got a good story of the QC guys drilling out the firing pin hole, firing a live round with the high speed camera.
Asked if he brought anything new and good to show off like the 48 with rail. Regretfully no, but a black slide 48.
And then, WHY they launched with silver.
Because when the 19x (at least the CB ones) "fell on it's face" the machines to make the slides in colors-other-than-black are just sitting there gathering dust. Glock Austria wanted to put the tooling they had invested in to work, insisted the new ones come with not-black slides, and silver was the agreed on one.
It didn't work out. The change is because they didn't make the expected sales numbers, and it's been proven to Austria already as US black-slide order rates are much higher.