The thing is though we've been told (for what that's worth!) they can't afford to do more than 2 episodes a story. So the best chance of a complete Wheel In Space (we have 2/6) would be find another 2. They'd then have the insentive to animate the remainder. Even if they just found 1 that would make it 50% complete, they might budge then.
Over time, the cost of animation will go down. Eventually, I'm sure all missing episodes will be animated. It might not be for another 10 years. But, someday it will happen as the costs continue to plunge.