The CEO of Stardock said that Sins of solar empire will go onto steam when portal, team fortress 2, and all those other steam-exclusive games get on impulse.
SO, unless you can convince your steam friends to break a deal with Brad, its probably never going to happen. So, basically, you have three options.
1. Buy Sins on Impulse today. You get the best strategy game of 2007, 20th best game of the decade,(https://forums.sinsofasolarempire.com/404714) + 2 expansion packs. Ya, so you don’t like impulse. guess what, I have good news for you! As soon as you finish installing sins, you can delete impulse from your hard drive, and the game will run fine. (Try doing that with steam).
2. Wait about ~20 years for sins to become abandon ware. It still won’t be on steam, just on your local abandon ware site.
3. Wait for some magical deal between valve and stardock, or one of the companies goes under. something intresting might happen then.
Besides, you don’t want the GOTY edition anyway, you want Trinity.
Seriously. I know you dont want to. But, I think you can force yourself to have impulse on your computer for a length of time no greater than overnight while you download the game. When I first got SINS, it was like.... I have to do this impulse thing? seriously? why?... grr... But, I suffered though it, and TRUST ME, it was WELL worth it.