We all know that there was a leak it probably a accident but one of the routes is the Brighton Mainline dose mean there a extension for East Coastway
No. DTG have said many times that route extensions are not going to happen. It is remotely possible that route linking might happen in the future, but it's not anything that's being worked on now.
This would be nice , but again - unlikely to happen . If this did happen though , maybe DTG could do the west Coastway , meaning that all 3 lines out of Brighton could be joined , also adding possibilities for services from Southampton/Portsmouth to London Victoria
How would extension and linking work? I’m assuming linking would be a “carry on this service” button followed by a loading screen? That could work if you were running a stopping service but immersion break if not