Nachfolger GS/GSA
I was wondering a similar thing about the basic R1200GS--it's nearly seven years since it was introduced which is a long time.
I'm really short of ideas what to do to improve it that would involve needing a brand new model. It's already lighter than the 700cc Honda Transalp. I'd be surprised if BMW raised the engine capacity as firstly I don't think it needs it, and secondly it would put it into a higher tax bracket in several countries.
If was in BMW's position I'd be in no hurry, there's still no serious competitor for the R1200GS in terms of taking sales away from it. Buell tried, as did Ducati, Moto Guzzi and Yamaha. And I can't see the rumoured Honda making any inroads.
If you remember, the R1150GSA ran alongside the R1200GS for a while before the R1200GSA was introduced in 2006. It's not had a change of styling since 2006, so maybe a face lift is on the cards.
Tim