There is a slight confusion here.
The Thameslink franchise is currently out for bids, with the new franchise starting in September 2013. As part of the new franchise, our Southern service will transfer to Thameslink in July 2015 when the current Southern franchise ends. Bids are being requested based on maintaining the current level of service.
The Thameslink programme which will see 24tph running through Blackfriars and St Pancras (the core section) is due for completion in 2018. As part of this, London Bridge is being remodelled with 9 through platforms and 6 terminating platforms instead of the current 6/9 ratio.
The information in the RUS concentrates on peak trains. We already lose the Caterham service in the afternoon peak (you have to change at Norwood Junction between 16:19 and 19:19 to get to East Croydon). In the morning, none of our services start further south than Norwood Junction, although we have 2tph to Caterham.
So after July 2015, all our rail services will be called Thameslink, we will keep 2 tph from London Bridge to Victoria and we will keep 6tph to London Bridge in the morning peak.
What is unclear is what will happen to our Caterham service, which goes via East Croydon. Will it continue to run to London Bridge, or will one of the planned Thameslink services from Caterham to St Albans and Welwyn Garden City stop here after the morning peak? There is scope for this to happen as the number of trains in the core drops from 24tph to 18tph. It all depends on whether they can get the train onto/off the slow line. Will we keep access to East Croydon in the morning?
What is essential is that we keep a direct service to/from East Croydon; Norwood Junction is a nightmare for those with luggage and we will get connectivity to Crossrail (and step free interchange) at Whitechapel when that is also completed in 2018.