What type of data are you wanting to move? Would you just want a huge movable block of space that you could mount somewhere?
Basically, it should be clear that all data connected to a person is irrevocably theirs. Any provider can build services for taking advantage of the data -- but it'd be the user's right to migrate it at their pleasure.
We need something like what happened with OpenID and Oauth. OpenID may be gone, but one company made a few bucks on it and OAuth is largely inspired by it. Someone needs to find a way to make a buck moving profile data around in a meaningful way then that becomes a de-facto standard that gets copied and used all over.
Then the government can regulate something that already exists rather than regulate something shitty into existence.
Of course this wouldn't lead to any magical inter-operation of services, but that wouldn't be the point anyway.