The new quad level cell (QLC) NAND provides a new 33% improvement in capacity at the expense of write endurance, Thee chips are better suited for secondary storage which does not change often such as with most games (DOTA 2 notwithstanding).
Toshiba, Intel and Micron all have been all developing QLC NAND mostly as demand for higher capacity has been growing.
Early SATA SSD drives have continued to be very popular and products are available up to 2TB are readily available. The lower cost 120GB and 240GB SATA products are the most competitive.
M.2 SSD drives are significantly faster but they require a pair of PCI Express 3.0 lanes. M.2 has been available for the last couple of years and over time the M.2 has become very widely used with desktop and recent laptop machines.
The increased density in each cell does come at some disadvantage,
The move from SLC to MLC showed that endurance did not suffer as much as feared. Database servers are comparatively brutal and MLC drives survived almost as well as SLC drives. In practice the move to QLC show it is still within acceptable market needs.
TLC cells are now the most common technology which has seen a lot of competition as the number of layers grows rapidly.
QLC cells are also layered but they still lag the TLC designs. TLC designs now reach 96-layers while the QLC are still 64-layer.
Intel has already launched their 600p series SSD for consumers with the new QLC design. The 600p range 128GB to 1TB.