Read the Crammond-interview already 5,000 times. And there hasn't been any news since then.
BTW:
Some of you are really excited about a possible GP5, but would a realease of GP5 really be that great as everyone thinks?
1. GP5 wouldn't have the official FIA-license.
2. A GP5-release would destroy the whole GP4-community.
3. We cannot expect the game to be without bugs. So we would have to play a game with lots of bugs in it for many years until SDI would be able to fix all of them.
4. In GP5 it would be very difficult to create mods, for sure.
5. Same for track editing, costums physics, new cars and so on.
So, as a result I don't see a possible GP5-release only as good. Crammond's physics are so realistic, they are out of reach. But his programs a buggy as hell
. At least the whole community would have to start from zero.