[quote name='HotShotX']The 360 has about 2x the install base of the PS3. It will happen.
~HotShotX[/QUOTE]PS2 had a larger install base and games like KOTOR, Dead or Alive 3, etc. were all Xbox exclusive. All consoles will have their own exclusives, that's all their is to it. And do you think Sony is going to let MGS4 slip from them with the amount they are pushing it??? I don't think so (DMC was not a series they really pushed over the years, unlike DMC). 2X the install base is incorrect actually, it's 1.5X worldwide.
Also, Kojima himself doesn't want to bother porting MGS4 anywhere, and Konami just doesn't have any other capable internal team to do it (their 2nd best team is their Castlevania team, but they are busy. Most of their teams are gone).
Late ports just don't sell, regardless of userbase. Viewtiful Joe did solid on GC, but when ported to PS2, next to no one bought it. MGS2 sold crazy well on PS2, but no one really bought MGS2 Substance on Xbox. Konami avoided a port for the third since they knew it just wouldn't sell as a late port. Lost Planet did well on 360 and next to no one bought it on PS3. Despite VF5 having more features on 360, it still sold better on PS3. Late ports just don't sell, because after 6 or so months, a game becomes old news and people want the newest games. Simultaneous games on the other hand can do well on two platforms.