Don't get me wrong, I would sign for it right now if I had a choice, and if, also hypothetically speaking, I could lure all devs to MeeGo, otherwise a good platform with no apps is not very appealing.
Symbian...unless they make it more modular like Android (i.e.: ability to choose default apps for everything) and integrated with sharing services (i.e.: having more sharing options in gallery than just FB and Twitter), I would ditch it for good. Its architecture is old. MeeGo is much better and flexible in this aspect and would have been a big hit, had it not come when Nokia's fame was at its lowest.
Right now, hoping in good sales for Lumias is a win-win because an improvement in the financial situation of the group could serve to keep other projects going in the background. In fact, Nokia never signed an exclusive to MS. They can release other phones with other OSes as well.