I don't think the 360 will cause a delay. At least not much of one. The game is actually being programmed on the PC first with the crystal engine which is already multi-plat. After they finish the game it's just a matter of porting it over. This was known (the PC development) years ago. The fact that the crystal engine was multi-plat was always a little fishy.
Edit: As per this article.
"Currently the game is being built on PC, where it's actually functional. We're still focusing on making it work on PS3, so it's difficult to know how long the process of taking it to 360 will take."
"Now that we're developing on a PC base, the pace is going a bit faster," Kitase said. "We haven't introduced new footage of the game, but we should be able to show something new in the near future."
So it's not even working on the PS3 yet. Yeah, I don't think the 360 will slow it down.
