I agree. I know there are certain times of the year that consoles and games sell better (like Christmas), and even if GT5 released at Christmas, it wouldn't be overshadowed by that many games....however, with that being said, GT5 could release at ANY time of the year and probably sell just as many copies and consoles with it, just because of the hype and the track record that PD has. They obviously make games that continue to wow the world, and with a game having as much support that it does, it could seriously release in the middle of summer when nothing is going on, and sell millions and millions of copies in my opinion.
Sure, if it did release at Christmas, it might sell more consoles with it.....again however, if it were released in the fall....I think it would be the perfect time for it. Us hardcore gamers could get our hands on it, and then for everyone else that wants it with a PS3 that can't afford it, can put it on a Christmas list or something. Sony would get the sales either way, but the monthly numbers might be split up differently. That's just how I see it, so hopefully what "makes sense" to them is that they would release it when it's finished.