This would not take out the cargo areas and LHR-4
You must be looking at a different map from mine.
Even if a runway was pushed as far south as possible, i.e. right up to the northern edge of the reservoirs, it would still point directly at T4 assuming it was oriented 09/27, as it would need to be.
This is a ludicrous plan, as will become apparent if and when we finally see a version that actually shows the runway itself, rather than the Evening Standard's "close-your-eyes-and-stick-a-pin-in-the-map" graphic.