Looking again at my post, number 12, I think I have implied that there will be no mix'n'match between the runways and terminals. There will be some of that in order to get the best use of the runways. There will be some crossings but the regulator is sure to pay attentions to the number.
Fortunately, the move towards twins for much of the long-haul demand brings such good departure performance that 2,200m gets you a long way at an economic load. This helps. One concern however is that Heathrow would become more wind critical because traffic would not be able to accept much (if any) tailwind off the short runway, whereas now there's some room for manoeuvre on that.
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