Agree with Heathrow Harry, especially when you consider that this would not come into effect for another 10 years so plenty of time to design and test any solution.
Consider as well, that there will only be a few airlines who this will actually affect (BA, Virgin, Aer Lingus...) as most operate widebodies into LHR anyway.
Not saying I agree with it, just that the hurdles aren't insurmountable