But the software that can display/convert them will shut down if it cannot access the cloud for too long or gets an expiration signal from the cloud.
Not exactly true, say you didn't connect to the 'cloud' (just an internet connection) for the three months you need. Those jpgs won't self destruct, if you have a windows PC you can open them in paint or preview on a Mac (which will open most raw formats too).
You can at any time stop using the Adobe software and still access your files (unless you choose to keep them in the Adobe server only–short sighted but acceptable as it's their iron)
The bigger problem is for other parts of the suite like Premiere Pro imagine having your projects stored in a file that can only be opened by that program.
Also programs like InDesign and Illustrator tend to have non backward compatible files, so if you keep your old CS5/6 when someone sends you a CS7 .Ai or .indd file you can't open it.
That's going to be a bigger issue from the pro perspective, someone who gets sent work to print etc.
If the server de-activates your software because of non payment you're files will still be there, and to a degree they'll be open-able or transcode into another format.
Activation has always been a bugbear but it's one both Adobe and Microsoft have used for many years.
My father in law lost his right to use XP because of the 'Genuine Advantage' system which effectively bricked his PC which was flagged as 'fake' software–he now owns a Mac.
So don't panic people, there are ways round just about any imagined impasse.