But it doesn't matter
With respect, I'm afraid you still don't get it.
The 5GB storage could be reduced to zero free storage. If you wanted to keep the wireless sync capability, you'd pay. Otherwise, you'd just use iTunes and wires again, exactly as everyone has to today. There's no lock-in and no requirement.
Are you reaching for your keyboard to say that Apple could remove wired sync support, perchance? Well why don't they just charge for wired sync or charge for iTunes downloads, then? They've had a decade to do it. Why do you think they don't? It's the same reason they won't charge for rudimentary iCloud usage.
Your "30 days" refers to Photo Stream. It's the length of time a new photo persists on Apple's servers before evaporating. As long as your various devices "see" a network within that time, any new photos will be sync'd down them. Once they're gone from Apple's servers, it doesn't matter, because they're still on your devices and always will be until you delete them - photos are obviously always on the device that took the picture as well as on any other devices that sync'd with iCloud within the 30 day period.
If 30 days was reduced to zero without paying, you'd just lose the wireless auto-sync stuff. So you'd go back to sync'ing via iTunes and iPhoto with wires. See how this works? It's an extra facility, for free, that takes nothing away from what you already do whatsoever.
iCloud is NOT a backup service or a remote data store. It is a SYNC SERVICE with no GUI. It's plumbing. Backup is still left up to the users through Time Machine or a third party network backup service. With Mobile Me going away, some people are complaining that paid services are being removed - DropBox should be ecstatic, because Mobile Me's iDisk was a competitor to them. Now it's gone. iCloud provides no arbitrary file storage, so DropBox just got some new customers. Flickr may pick up some Gallery refugees (the iCloud photo stream is - once more, this time with feeling - just a sync service, not a gallery engine) and there will be a few web hosting companies enjoying picking off ex-iWeb people too. Of course iCloud may regain some of this in future, but if so, it'd only be going back to where MobileMe used to be.
Apple aren't treading on toes - if anything, they're actually stepping off a few.