I suppose it's possible. I remember around the time GT5 released, Red Bull released an article that confirmed that Pikes Peak was in the game with an interview with a driver who compared the real track to the supposed in game track. I'd bet anything that the track was slated to be included, but was later canned because of time.
Uphill and down. Really miss this - reckon it'll ever appear again??
I'm not holding my breath for DLC. It's been too long since release and no announcement compared to other games.
On the other hand, knowing how PD operates it wouldn't surprise me that much if it just showed up on Tuesday with no warning or explanation whatsoever.