I've also pondered the possibility of Hawaiian or even Alaska eventually joining ST, especially given their current relationships with CO and NW. DL has long been the only major without a code sharing arrangement with either Hawaiian or Aloha. That said, though, I don't think Hawaiian, Alaska or the others you mention (with the possible exception of PAL) are large enough to make full membership in ST viable for them. I agree with the other posters that Malaysian would make a great addition.

I believe the real plum for ST would be JAL. They are by far the largest airline out there still uncommitted to an alliance. I'm not sure KE would welcome their membership, but I sure would and they have great coverage throughout the world. I hope someone in ST is chasing them hard.