More like an unrealised dream. The land take when the original line was built was bordered by roads of victorian houses built in the late 19th century from east of Maryland to almost Goodmayes. As it stands, the line is about 3-5 metres below the surrounding ground level and what was originally soft embankments over that stretch is now fully lined with walls of engineer's blues.* With current land values, especially after the rush for housing near Crossrail stations, any increase in the formation's width would be prohibitively expensive.
* Except for the stretch at Aldersbrook by the River Roding where the flyover is.