Earlier quoted context omitted.
There are a multitude of VPN services in the market already. The generally accepted "best practice" for those with VPN service is to use it everywhere (not just on the road). When you're paying monthly, most people feel incentivized to use the service as much as possible. I've set up VyprVPN for a couple of ultra-paranoid friends, and the whole process was very smooth and end-user friendly.
And there were plenty back-up services before dropbox.
There is nothing new or unique in what you described, with the exception (maybe) of automatic initiation of VPN services when you're on "public" wifi. I would argue that this is a differentiation of little or no consequence, because there's no reason to not use a VPN all the time.
You basically described every personal VPN provider in the market as a start-up idea.