What I would prefer going forward is m.2 sockets fitted to cases (replacing 2.5" SSD sleds) that connect to nVME channels on the motherboard (as more channels become available on CPU's) via a slim cable similar to SATA. I know that something like this is already available in the server world (u.2? although could be wrong with the terminology as not that up on enterprise gear), but would like to see this become mainstream in consumer systems.
As for new SATA specs, I think that it is coming towards the end & moving forward with nVME would be a better option IMHO. If SATA manufacturing was ceased & put into nVME manufacturing/development, the prices of the lower end nVME (which is still faster than highest end consumer SATA), we would start seeing the cost per Terabyte on nVME come down to similar levels of high end SATA storage with lower power overheads. If going forward with SATA type devices, consumer grade SAS would be a nice replacement.