Again i feel i need to point out the whole "360 doesn't do well in europe" thing is bollocks.
With this weeks numbers we could see 360 outsell PS3 for the year in europe. That shows europe is very much a 50-50 place.
However in UK which is the biggest region for games and last gen was major pro Sony has changed to pro 360. GT games sell loads there. The fact Sony is no longer the cool thing there will have an impact on GT5 sales. This will be the first time a GT game has released on a format where it is not the main selling console. In fact it will be the format in last place at the time. Again that will have an impact on sales.
As others have mentioned GT3 came out soon after the console was launched. GT4 had around 140m consoles to sell to and sold less then it's predacessor. Meaning that more consoles doesn't always mean more sales but also meaning a game released later in the consoles cycle doesn't always mean higher sales too.
The exact same thing also apply's to Halo Reach. It is being released later in the console cycle and with more units to sell to. Doesn't mean it will sell more then Halo 3. Personally i don't think it will beat Halo 3's numbers. I think it will have a bigger opening then Halo 3 but come up a little bit short overall. I expect 10m for Reach. Based off of the sales from US and UK. We know from the tracking that it is going to sell well. It will have well over 1m pre-orders with over a month to go. Making it the highest pre-orderd game ever most likely.
People use the whole "it is tracking alongside MW2" thing but how much longer will you be able to say that?
Next week marks the point when GT5 reaches the 12th week mark. At that point MW2 started to be tracked. Each week from that period on MW2 had over 20k pre-orders each week. And then in the next month it never dropped below 40k. Meaning next week GT5 needs to start doing 20k pre-orders or it will begin to fall away from MW2 numbers. At that point people won't be able to say it is tracking alongside MW2.
It seems to me that the whole defence of GT5 numbers is based around the MW2 comparison and that in europe it will sell millions. Europe has changed since the last GT game. To give you an example of that. Last gen by the time of GT4 released in UK alone PS2 had sold 7.5m units. This time around PS3 has sold only 3m units. A difference of 4.5m units. Which again will make a huge difference to GT5 sales. And as mentioned above the MW2 comparison will bite the dust in the next couple of weeks.
So no, logically GT5 will not sell as much as Reach. It will sell very well. Probably around the same 8m mark MW2 is at on PS3. But it won't sell above that mark. More people are interested in FPS games then Racing games, it is as simple as that.