Given they've made it very clear PS3 version will be finished (and released in Japan) before they even start 360 I don't see how it could be affected.
What interests me in light of recent news ID may (I repeat may to be clear) reduce resolution of textures on 360 to get it on 2 DVDs I'm curious whether FF will simply spread over 4 or 5 disks or whether SE will adjust any content to make fitting the game onto multiple DVD's easier... that's of course assuming the game will need more space than one DVD can deliver...
I'm also curious how SE will react if this sells like gangbusters on PS3 in Japan and they come under pressure to get it out on PS3's WW without waiting for 360 to complete. Unless they have a contract with MS now (which would mean MS did buy the release dates outside Japan being wedded at the hip) they could chose at any point to get it out sooner WW if the change their mind again - and let's face it there's plenty of evidence SE can change their mind pretty quickly when it suits them.
Try to be reasonable... its easier than you think...
