Unfortunately, as it stands right now, even with rapid growth, ransomware is approaching its infancy. I'm not going to be surprised when the next CryptoWall releases go after Active Directory and enterprise-level resources, as opposed to local items and the network share or two.
Three reasons why this is:
1: There are no SOHO backup systems to defend against it. If you can get the user to not restore in 30 days with most cloud backups, their data is gone... and some cloud backups may just only keep the latest (useless) version. Plugging in a USB flash drive, backup drive, using a NAS, or using a Time Capsule works against disasters like HDD failure or accidental microwaving of a laptop... but all ransomware has to do is zero out the backup drive... or just punch random holes in stored files so they are worthless. A lot of newer machines don't have optical drives, much less decent backup software to get the user to back up to them.
If you want a real defense against ransomware, it takes an external backup server which pulls data, stores it where the client machine cannot access or destroy it, and can store images for weeks to possibly years (because as ransomware evolved [1], it will be running longer before it gets detected.) However, not many home users will buy a PC with some drives, slap Windows Server 2012 R2 Essentials on it (which replaces Windows Home Server), and use that to pull backups from their desktops. There are appliances that do this... if you want to pay $50,000 to Symantec for a NetBackup appliance, and have the rack space for it.
What is really needed is a standard, cross platform backup client that not just allows for files, but snapshots (so open files can be copied) and entire machines, so bare metal restores are easy to accomplish, be it a restore to a local drive, or via the network. For authentication, something similar to SSH. This way, a user can buy an appliance, log onto the console, set up backups (perhaps RSA key exchanges), set up schedules, and call it done. More features (encryption, deduplication) can be added... but the main thing is getting backups going in the first place.
2: The infection vectors are still there. For example, a malware writer might write code to take advantage of a compromise/buggy browser add-on, it goes through an ad server, and winds up nailing people visiting even mainstream sites.
Even ten years later, the Web browser is still the primary infection vector. Even with virtual machine and container technology, if an add-on gets nailed, there is a good chance it can seize the entire browser, and thus a user context. Even with just the context of a browser add-on, it likely can read and write to any documents the user has access to. Add a few more exploits, it can run unfettered as a user, or even get admin/root rights so it can reflash the firmware on drives, video cards, keyboards, and other items.
This can be limited by running the browser in a VM or sandbox, but most users won't be doing this, so it is only a matter of time before the next add-on has 0-days, and just visiting a site results in compromise.
3: Not as bad as drive-by compromises, but Trojans are still an issue. On Linux, BSD, and OS X, this is less of an item, since users are conditioned to use a repository. Windows still is wild and wooly when it comes to this, and even if one does visit the right download site, it might be a mirror decided to pack some additional "functionality" into the installer, and re-sign that with their own Authenticode key, so it passes the signature check test.
The possible fix? MS having a store that allows for more than just Metro applications to be installed and updated, preferably with active, brutal curation. That way, if a user wants a copy of WinZip, they just fetch it from the store, rather than risk a compromised website, mirror, CDN, or app installer.
Ransomware is going to be with us a long time, just because it does well at going after the low hanging fruit, and with what is available (domain admin rights, for example), just encrypting files is just the initial salvo in this battle.
[1]: It pretty much a fact that malware, as a whole, is the absolutely best code when it terms of quality, robustness, and updates.