I'm sure the next version of Office will be optimized for the new Win8 UI style or at least have a companion version that's optimized for new Win8 style, but it'll be awkward for Microsoft if that next version isn't out until ~8 months after Win8 itself, which is very possible given that Office 2010 came 8 months after Windows 7 and they usually have similar release cycles.

(Were it up to me, I'd make damn sure Office 2012 is ready day-and-date with Win8, and accelerate the release by cutting absolutely anything, other than support for the new touch UI, necessary to make that happen.)