This answers a question I posted on the YouTube video's page. That's awesome. I mean, the loading times in Forza Horizon 4 generally aren't that bad outside of initially loading into the game from the title screen and coming out of events and/or changing seasons, as the presentation going into a race masks the loading times. That said, it'll be interesting to see how much more quickly the game loads. I was going to put it on the internal storage, anyway, since I still play it so much.
Like Richard says in the video, the improvements we saw in BC games so far are only thanks to brute SSD speed, but there are other ways in which new/patched games could take advantage of next gen consoles' architecture, beyond that.
Decompression happening on the fly means you can load compressed data, so smaller files.
Furthermore, with access to data being this quick and having no impact on CPU games won't need to store everything in ram, instead they can be structured so that they only stream data as needed, potentially allowing you to start playing in seconds while the rest is being loaded in the background.
Not sure how much of that Playground was able to implement in a patch, but if what we were told is true we really haven't seen anything yet.
