The Elizabeth line runs from Reading/Heathrow, through central London to Shenfield/Abbey Wood in the east. MAP: The train used is the Class 345 EMU: I would love to see this in the route, possibly as an extension of the GWE route. I know it's long but would love to have it (or at least part of it) in TSW.
I think this is about 3x the length DTG usually does, so the chances of getting all of it are slim. It's a pity because it looks like a very nice route.
I am pretty sure that they wouldn't do at least the western end as that would be GWE. In addition, there are little to no references of the stations and tunnels in the central section. The only new bit would be the GEML and or the Abbey Wood branch. I would assume that the GEML would be the most likely part of TFL rail as it would be a new route.
They probably won’t repeat a route they’ve already done, so if it is added it would be the other direction from Paddington.