In an interview with VG247 he cites "business reasons" for the decision, but explains that there is no reason why the game couldn't come to PS3.
Thats probably more of a business decision, and one that I wasnt part of when I was at THQ.
The studio architect of the 4A engine did a lot of the initial work on the PS3 first, just to get to grips with the architecture.
A lot of the early prototypes you saw were of the PC version Youd probably have to ask someone up in senior THQ finance to find out why we didnt greenlight a PS3 version at the time, but theres no reason why the engine wouldnt work on PS3.</blockquote>
Baynon later added that 4A Games now have the PS3 architecture in place, so any future titles developed by them will see release on the Playstation 3 too. Which is nice to know. Whether we get a port of Metro 2033 down the line will probably depend on how well the game is received on PC and XBOX 360.