I believe there are other less bombastic gains from having an SSD as a baseline, that will still impact the way games are built and organized significantly.
Things like voice, sound of video files can also be fetched on the fly. That does not seem like a huge win memory-wise at first, because on typical games TODAY those occupy a meagre portion of memory. But that is because games are designed in such a way that this is the case. But with the zero-seek time, a game can be designed to have a huge library of sounds and video (and other things for that matter) from witch it could fetch few random small clips from at any moment with negligible impact to performance.
So in-game radio's and TVs for example, can fetch clips from any part of the game's entire library, completely unpredictably. The sound and video files can be separated into single second files, so no more memory than the absolutely minimum necessary has to ever be resident in memory. Fetching a thousand 10kb files from an SSD takes about as much time as fetching a single 10Mbs one. And doing so in the middle of fetching some other larger and more important asset does not disrupt it's loading at all.
You can have a TV sotore in a GTA games with 5 different TV stations playing simultaneously, with non-repeating content (unless you stay several minutes watching it that is - and even then, they could randomize the order the content plays on each so the repetition is even less noticeable) That is not game changing, but its a nice detail. The same concept can open up a lot of cool possibilities. Magazines and Newspaper covers on Newstands with randomized content every different time you come across them, with a sprincle of narrative-related stuff in there (mentioning previous missions). Same for Bill board ads, characters clothing, stickers on NPC's cars, grafitti on the streets.
An open world game could allow a player to place hundreds of different grafitti on any wall of their choice, out of a library of thousand different designs, with minimal impact in the game's texture budget, and very little planning ahead by the dev.
All of this is stuff, of course, could be done before, but it required some amount of planning, and so were implemented in a very limited fashion and with free random seeks, it becomes trivial and can be all over the place, all the time.