One idea could be to make a weird mix of WoW, or rather Tabula Rasa, and EVE-Online. You could be able to pilot different ships in space and do PvP with them, as well as missions that included killing hostile flying units, like Mutalisks. You would also be equipped with a warpdrive so you could get to different solar systems and land on the planets for trading and ground combat.
When it comes to the levelling system, it could be a bit like EVE, where you buy a skillbook and "reads" it to gain the skill. But rather than spending days getting the skill up, it should just be like you read a manual to see how the thing worked. This would take somewhere between five minutes and two hours, depending on what item you wanted to learn how to use. A gun would take a small amount of time to learn to use, while a spaceship would take longer. More advanced guns/spaceships would require you to have the skill to use less advanced versions. After your character have read the manual, you will be able to gain experience using the item. The more you use it, the more experience you gain, the better you perform using the item.

What do you think about it?

2 years? People have fantasized about a SC MMO since MMOs became a reality.