Crosrail has morphed into Heathrow connectivity which to be fair is bizarre. It was always designed to support Londoners in the West getting to the East. It has now somehow become an artery of Heathrow which in some resoects is good for Heathrow passengers but a total disaster for London commuters.
The fact that Crossrail is connected to Heathrow is a good indicator that planning was intended to serve people getting too and from the airport. It will also have an impact on LCY as it will suddenly make the City, the Wharf and Heathrow a lot easier to travel between. The Shenfield to Reading market by comparison, is tiny. It won't be a "total disaster" for anyone if people traveling to Heathrow use the new public transport option, it really, really won't