Games are already taking advantage of the faster IO, we don't need to wait 6 years to see the benefit. The major benefit is to game developers, to the end user you might not notice anything other than super fast, seamless and more detailed games. How will that lead to disappointment? I really do not understand. There is a serious lack of understanding of the benefits of fast IO as it pertains to game development. This is not the fault of Sony or Microsoft but of people not understanding what they are being told. Nobody oversold the importance of fast IO. If we rewatch the Mark Cerny Presentation or look at Microsoft's marketing material they underlined few key things that having fast IO enables.
For developers they underline
1. More available RAM for render budget. You don't have to keep a lot of assets in RAM as a buffer for what might be needed, you only have what you need in the next few seconds of rendering and load as you go. This frees up lots of active RAM and means you don't need to increase RAM. (also means less cost for Sony & Microsoft).
2. No need to design to hide loading. Developers spend lots of time adding sections to artificially hide loading. A recent example of that is Ghost of Tsushima, they added pre-rendered cutscenes to hide transitional loading between environments. On PS5 all cutscenes are now rendered in engine because the SSD is fast enough to stream in the new environment as needed.
3. Less assets duplication to hide seek times and latency. Keeps games sizes down and again we can see that game sizes have not really ballooned significantly, accompanied by really good compression technology.
These are 3 quality of life changers for games developers as they spend less time trying to optimize around slow storage. For example of how that hampers game development see
Postmortem GDC talk on Spiderman. How that may lead to some really cool new game mechanics will be interesting to see. It also benefits cost of development in small ways.
For Gamers they underline little to no load times. This is self explanatory and we are seeing more games have less than 3 seconds of loading. And more detailed games.
That is literally it. I challenge someone to find anything from Microsoft or Sony that oversold what fast IO enables.
You won't.