There would be a technical problem in that the wires don't extend to Shepherd's Bush so this would need to be resolved. As mentioned by another poster, this has been proposed. It doesn't affect anything like the operation of the emergency door releases so there is no issue. This is how it's done on parts of the NLL with 313s.Would safety be compromised by moving the switch over point to a station, say Shepherds Bush?
What I don't understand is why it can't be done whilst the train is still moving, as how it used to be done on the Eurostars.