There is a growing belief that Sony may be planning on offering expandable storage in the form of SSD cartridges for the PlayStation 5. A patent drawing originally thought to be a game cartridge is now being reconsidered as a possible straightforward external solution for supporting the PS5's internal custom SSD when it is reaching its storage limits.
https://www.notebookcheck.net/PlayStation-5-console-might-come-with-expandable-storage-in-the-form-of-external-SSD-cartridges.442703.0.html
It would be great if the Blu-ray drive was optional, sold apart.