I'd hunt the same places now as I would earlier in the year. Grouse don't migrate due to snow and actually need snow to best urvive the winter as said earlier. Grouse pick habitat that has year round food and cover so they don't have to move as the seasons change.
The only caveat regarding late season grouse hunting is to not hit any covert too hard. Grouse taken after the fall shuffle often leave that cover open until the shuffle next fall. It isn't much of an issue in marginal habitat where survival is questionable in the best of times but can lead to some long term population drops in heavily hunted or isolated areas.
