I hope you are right. Either way though, Fellaini counts as one of what is likely to be a group of four midfielders now that he is here. That means that, if he stays here as is assumed, then in all likelihood, a couple/few other midfielders will have to leave for numbers sake. I can't think who they would be.
At the beginning of the summer, I think most people thought we could carry another two in there, and that is with Anderson leaving. Now, even if he does leave, adding another two to Fellaini will probably leave us over-crowded. And as it stands, the idead of not adding another two because of Fellaini is very annoying. So whether his purchase has exhasted resources in terms of budget, or just squad space, his purchase is still likely to come at an opportunity cost of better and probably more useful midfield players.