Well apparently, SWBF3 was originally being developped by free radical, but as crazzy said, they went bankrupt. According to rumors, they are being developped now by rebellion development.
And seriously, I think that bringing out SWBF3 will get them a great income coz I'm sure many are waiting for it. Maybe they'll develop it once they get money in from Star Wars The Old republic. Since there will be a monthly fee, they could use that money.
I really don't see myself playing shooting games like SWBF2 on Wii. According to friends, the Wii is fun at first, but then it gets boring...