The next significant project, after T5 opens and the second T5 satellite is built, is to rejig the taxiways around the main terminal area (especially now Rwy 23 is closed) so they enclose a rectangular area rather than the present somewhat cut-into area due to the original runway pattern. Then the space gained will be filled up with additional terminal extensions.
Looking down on T5 from a departing aircraft a couple of days ago, was interested to note the roadways etc still have a lot of work to be done on them (despite the M25 connections seeming complete), and the main buildings have a considerable way to go too, yet the stands at the satellite are already in extensive use for overflow aircraft parking by T3 operators. Is anyone being bussed from the terminal to these stands already ?