Hmm, bit worried about the people from dirt and grid being involved here, their games are rubbish in terms of realism/dynamics compared to Forza and Grand Turismo!
yh but there saying that is a spin oof game from forza, not a follow on from forza 4, forza 5 will still be coming out next year
As much as they say that Forza 5 will be coming out I can't help but agree that bringing in the development team from Dirt and Grit bodes ill for Forza. With Forza 4 Turn 10 really made quite a feature of the increased cinematic atmosphere with the flames popping from the exhausts (and even the rewind function). Forza has definitely been influenced by Grit and Dirt and I - as much as it pains me to say it - suspect that even more of such games will impress upon Forza's gameplay.
As for Horizon, it really would be nice if Turn 10 were going to release their own "TDU" but I don't think it's very likely. TDU took a long time to develop due to the sheer size of the environments. As detailed as Forza is none of the tracks are even remotely close in terms of scale to the environments of TDU (1 or 2).
Ah well, we shall wait and see.