At the end of the document, TfL do some star gazing and attempt to show us London's Tube & Rail Network Map for 2015 and 2019. Look at page 85 and page 86 of the PDF to see the maps in detail.
The biggest change for 2015 will be the completion of the London Overground with an extension from Clapham Junction. This will make the Ginger Line, much like the M25 of the rails. There's a cable car connecting Royal Victoria and North Greenwich and the DLR will extend from Canning Town to Stratford International.
Zoom forward to 2019 and you'll see the purple line of Crossrail running through the map. Note the heavy blue lines marking the interchanges at Barbican and Farringdon. No idea what they mean at the moment but I'm sure someone with a greater knowledge of Crossrail can enlighten me.