You know it, in my reviews I have been complaining for a year or so now that the developments for the SATA interface are not progressing. Most SATA3 SSDs these days are limited by the more narrow bandwidth the interface offers. As a result, we've seen SSD NAND storage in the form of M.2. on the rise for a year or two already. 

M.2. is making use of the PCIe interface, often using a 2x or 4x PCIe 3.0 lanes ensuring you can even reach the 1 to 3 GB/sec marker compared to the ~560 MB/sec marker SATA3 offers. Sales are now reflecting this dynamic, there is a sharp move towards PCIe based NAND storage. There's another factor involved, NAND is getting cheaper, making fast NVMe PCIe based storage more affordable. PCIe SSDs are expected to become the new mainstream by the end of 2019 with a market share of 50%. Apacer Technology president CK Chang said that with better performance, consumer PCIe SSDs will gradually replace SATA SSDs. 

Market sources said that unit price for 512GB PCIe SSD has fallen by11% sequentially to US$55 in the first quarter of 2019, compared to a corresponding price drop of 9% for SATA SSD, with price gap between the two types of SSD continuing to narrow from 30% seen in 2018. The sources continued that current average unit price for 512GB SSDs has declined to the same level for 256 GB SSDs registered one year earlier, and larger price falls for SSDs ranging in capacity from 512GB to 1TB are expected in the remainder of 2019.

PCIe SSDs slowly replacing SATA3 SSD