The Japanese website 4Gamer published an article with Sony in which it is mentioned that the new PS4 Slim and PS4 Pro would use the SATA 2.0 Interface.
However, since then a correction has been placed up to clarify that the PS4 Pro will actually use the SATA 3.0 interface. This basically means that the transfer rate has been doubled from 3.0 Gbit/s to 6.0 Gbit/s. Whether this means that there will be faster transfer and installation rates for games will remain to be seen until the console is launched.
The PS4 Pro launches on November 10th, so there isn’t long to wait until we see what happens.