I don't buy that either.
If GW don't release SG it won't have anything to do with worrying about losing 40k gamers. Going by that logic we wouldn't have space hulk again, again.
I'm still not holding my breath for any of the SG to be re-released mind you! I think as people have pointed out it could well be in connection to other products such as video games!
Would love for gorkamorka and necromunda to be re-released though :<