The 3D TLC 2.5-inch SSDs will range from 256 GB up to 2 TB with AES-XTS 256-bit hardware encryption, TCG Opal 2.0, eDrive, and optional desktop installation bracket kits. The 256/512 GB capacities are now shipping while the 1/2 TB SKUs will come at a later date.
https://www.notebookcheck.net/Kingston-launches-KC600-series-for-users-still-stuck-on-2-5-inch-SATA-SSDs.439546.0.html
What's this "still stuck on 2.5 inch" nonsense? Even for most high-end consumers (not prosumers running large CAD, video rendering/streaming, HPC programming, databases, or performance benchmarking), the speed of the Samsung 860 Pro, Crucial MX500, and whatever is Sandisk's latest are pretty much identical for OS loading, game loading, saving office documents, saving a screen capture or recording, etc., and they're all more than fast enough.
If you're on a thin&light ultrabook, or all you're going to have is 1 drive in your desktop system, then sure, make it an M.2 and save yourself the cables/bulk, but let's not kid ourselves. Most consumers will notice SSD vs. HDD, however most will NOT notice NVMe vs. SATA III.