What happens when these "cloud" companies go out of business?
You're pretty much SOL if you can't find a replacement quick.
Don't ever rely on "cloud" software for critical infrastructure unless you own that cloud.
Everybody get CS6 and delay upgrading as long as you can.
The problem here was that they added DRM to it to make sure you can't use it if you don't have an active subscription and those 'call home' servers failed.
It is more of a DRM problem than a 'cloud' problem.
Everyone who seriously considers moving mission-critical software or infrastructure to the cloud should (if they don't already) have a contingency plan at the forefront of their evaluation of any platform/service. Evaluations of solutions like that take away much of the risk that you're proposing. It's also just smart business.
I ask for open formats from people. Send me something I can work with in my choice of software! Save multiple versions and deliver those just for redundancy. There's no excuse if you're using pro-level software to ever say "well I guess you'll have to buy it to do something with this"