IMO, pro cameras will soon see 2-3 TB internal SSD's with the highest speed USB of the moment (presently 3.1) used to offload files. Right now, a 1TB Samsung (540 MB/s) is $499 retail. With the HEVC compression, a 4K ProRes 422 quality file can be squeezed into ~ 150 GB/hr size. Double it for 4444 and you can still get three hours worth of shots on 1 TB.A small form factor SSD would be awesome, right across the board - Cameras, PCs, Recorders, backwards compatible with a 2.5/3.5" caddy, capacities up to 1Tb.
It's so useful and obvious that it will never happen.