So building new runways, terminals, baggage transfer tunnels etc. wont solve the problem of an airport running at capacity?Not sure I understand the logic there.
The whole plan for the redevelopment of LHR is based on making the transfer of passengers and baggage easier and more streamlined. This will make it more viable as a hub. Crossrail will make it more easy to get to/from London for passengers using it as a starting/ending point. It is next to both the M25 and the M4 so easily accessible by road. The airport provides jobs to a large area of west London & the Thames valley.
What it really needs is a rail connection from the north, south and west that doesn't involve going into London and back out.