In such a situation, I foresee something more like the splitting of the Roman Empire. There's no reason to stop serving global customers just because the users are separated from HQ. Especially if the servers are already on both sides of the geo-political border.
The Roman empire had a tradition of splitting the control of the areas between multiple people at several points starting from Diocletian's tetrarchy onward.
The last east/west split was different on that it was that last one.
In a way, you could look at the period of absolute control by a single person as an exception in Roman history.
