Quite frankly, the order that the expansions get work should be a function of "how much needs to be done" and "future potential, meaning which way people shift from expansion to expansion, almost entirely old to new", and "how much money is donated". Where the how much money and potential future should be most important. What is the obvious missing variable? How many current players are on each expansion, because it may seem obvious but it really is irrelevant if you really think about it. If a ton of people are playing wotlk that doesn't mean it needs tons of addl development, but the opposite that it is in really good shape already, and that people are "stuck" there. If you wanted a true measure of where people want to play, there would have to be free and easy open character transfers between expansions.
So where should most of the efforts be? It should be only weighed by how it will help Warmane for the future, and how much actual money is being donated to pay for current development. It seems to me Loreadon will have nearly no $$$, so thats just a staff pet project, not a good business decision. That being said, 10x of the development should go MoP until 95% done, then 5x can shift over to starting a new WoD development. And wotlk should be 1x because it is very close to done, and 2x to cata - if they want to keep a cata going. If they plan to close it (which I think is best), then 0x.
But all indications are, mop is unimportant compared to a tiny profit pet project, it may be time for serious MoPers to find a new place to play if you are unsatisfied with the current state.