.....Last I knew the plan for c. 2030 (i.e., what was then meant to be post third runway) was for a T5X to the west of T5A, providing a substantial increase of gates around the main building, and T5D was at this point unlikely to happen.....
The new terminal facilities included in the third runway proposal, involve a new terminal to the west of T5, arranged back to back, with T5. Although separate terminals, they are linked together airside, to create a large combined terminal complex.
The only new gates to the west of the current T5, would be those attached to the new terminal building.
The majority (most) of the new gates and parking stands associated with this new terminal, are proposed to be remotely located on the north side, between the current northerly runway (09L/27R) and the proposed new runway.
Under the Heathrow development plan, T3 would be removed and replaced by a much enlarged T2 with a large number of additional gates.
The plan results in what has been described as a “toast rack” layout, which adds two more satellite piers similar to T5B & T5C, located on the current T3 site, one of which would be an addition to T5 and the other associated with the expanded T2 complex.
What happens now, with no new 3rd runway and uncertainty over how a post- COVID-19 world will pan out, is unclear.
The new terminal and gates to the west of T5 will not be built without the new runway, but HAL still have an ambition to replace the sprawling and dated T3 with the planned development of T2 and the revamped and realigned central area.
If that goes ahead, T5 is likely to get its new gates.
z