I doubt the datacenter's locations matter. The services at the bottom of the stack need constant ops to stay alive. With most of the engineers out, I expect barely a few days to go by before one of the essential services needs servicing.
For companies that size, the really important services probably have a distributed ops team, with a team in Europe/Asia alternating 12 hour oncall shifts with a team in North America. In an emergency, the non-North American team could take 24 hour shifts to keep the infrastructure alive.
Though of course if headquarters was really wiped off the map, there'd be huge problems with communication, tribal knowledge that only existed in the heads of senior engineers in Seattle, and so forth.
