No, for the current configuration to work, you would have to create a way to move data in both directions from the "old" backend to the "new" backend. Ideally,

No, for the current configuration to work, you would have to create a way to move data in both directions from the "old" backend to the "new" backend. Ideally, you would slice up the beast so you didn't have to do this with everything all at once. It's not a system that would be ideal for something transactional like a bank, but it may have been possible for an organization like Digg.