I'd be totally happy with both modes being completely independent. Cloud-synced files could take care of shared state for a lot of usecases. I mainly just want this for the portability aspect with the phone.
There are some practical issues with having to make sure you have the screen and keyboard access (in practice the all-in-one of a laptop is pretty handy - though I guess you could still have this form factor in a much lighter shell minus the compute) but for a lot of cases like home <-> office this would be the dream, just carry your computer in your pocket.
