I'd much rather O'Shea left before Fletcher, he's terrible. It frustrates me when Sheasy plays midfield ahead of Fletch. After last season's experiment, i'd go as far as saying Fletcher is even better than O'Shea at right-back.
Anyway, wouldn't be suprised if Fletcher left, he obviously won't get a look-in here, with Carrick, Anderson and Hargreaves ahead of him and young enough. Queiroz even said Veloso would become a priority if one of them left, so even if Carrick did depart as some are suggesting, Fletcher may still have no room.
Personally, i have no real view on this. We'd survive if we lost Fletcher, he won't disrupt much if he stays, so i basically couldn't care less.