The world will continue to run on cloud platforms even if PS360 offer only single player games. ^_^
There are tons of money invested in cloud computing. PS360, iOS/Android, PC/Mac will all benefit.
e.g., FFXIV is an MMO announced for PS3 and PC (Coming August 27 2013). In China, Shanda is supposed to be the publisher for FFXIV.
Shanda also launched an Amazon-like beta cloud platform in 2011:
http://www.gamelook.com/?p=1121
It includes cloud storage, cloud host, cloud monitor, cloud database, CDN, etc.
When FFXIV is localized for China, Shanda will just run all the servers on their cloud infrastructure. PS3 and PC users won't know what the game servers run on.
Now, there will be R&D to continue to improve cloud technologies, just like everything else. But it is "everywhere" today.
The developers may try to make a unified, seamless world as they continue to tinker with the technologies.
You can bet that SOE's Planetside 2, EverQuest Next, and whatever MMO games coming will be on the cloud too.
Now if Gaikai came through, standard SP games can be served via cloud streaming too. In which case, everything also runs on the cloud. We won't be able to shoehorn what the servers can or cannot do.