PS5 will really have the space advantage when the SSD slot is enabled. A additional 2TB will go a long way, whenever that happens though.
I guess Microsoft can just release a 2TB card as well though.
In the long run, this might be better. But I really hope that the expansion slot of the xbox won't be seagate exclusive for the whole time. The cost-driving factor of that stick is, that is just uses one chip (high frequencies needed).
The expansion slot in the PS5 will be interesting once the m.2 SSDs aren't getting that hot. Cooling is a big problem, because the SSDs are reducing speed if they get to warm quite fast. Sonys solution to that problem was using 6 chips, so the heat is distributed quite well by design. But an m.2 SSD does normally not have 6 chips. So more heat is produced on a smaller area that is much harder to cool. I guess Sony thought that the industry would be more advanced at the launch of the PS5. So it needs a little bit longer to get that m.2 support out.
But I wish they would at least support m.2 SSDs for ps4 games.
While the GDK made it easy for devs to develop on PC/Xbox, I think that made them sloppy as well and packaging the whole thing in one file. Similar to PC when you choose your settings according to your hardware.
If I could decide if I publish one package that runs all machines or 2 packages with extra work (and a completely different toolchain), I would always decide to use the one-package for all system. Much easier to support in the long run.
Always when someone above me, decided that we release the same product in different packages for different target-plattforms (well same plattform but different iterations) we had more work with the support in the long run, because we had always to create 2 packages (ok, most of this is done automatically) but must always be managed twice (updated to the toolchain), always installed and tested twice, create readme-files twice, setup-files twice, ....
It is much easier to just have one package to serve them all
But yes, it also make you adopt newer stuff much slower. But you get even slower when you must always extra check the old path (in the long run).