Haven't you seen the G2 plans on the Stansted website? Try watching the video - it's all happening Southside.
http://www.stanstedairport.com/porta...0357e120a____/
There's no expansion plans Northside other than development of Long Stay Car Park. Cargo will not be going anywhere and if anything will develop further Southwards from the Zulu apron and/or West towards the SRT Diamond Hangar.