Uefa, with all their faults and corruption will already have a contingency. They'll have contingency against terrorism, plane crashes, earthquakes, assassinations etc etc. There'll be a plan B, C and D.
I know it doesn't suit the agenda of this Board or others but there will be a plan. Surprisingly there might not be a queue to host this event because it'll strike a venue from holding again in the foreseeable.
Portugal is the most obvious candidate if it's outside England and for me it should be outside, because Chelsea v City at an English venue just takes the gloss off things.