What Manchester needs and more importantly needs to sustain is a long haul carrier of it's own. Lets face the fact we will be waiting forever if we rely on BA, BD and VS. Overseas based airlines cannot be relied on either as witnessed by SQ,s strange decision to drop two of it's seven weekly flights (Is this so it can help fill it's London originating A380,s).
Yes i know raising the finance for a startup airline is hard at anytime, but i can see a carrier with six Boeing 787 ,s flying non-stop to west coast USA, HKG, and competing with the incumbent airlines to New York, Dubai etc.
Take off and landing slots are far easier to come by at MAN than LHR and as regards ticket prices a new start up carrier will be able undercut the legacy airlines.