My guess would be the great performance increase due the polishing. I suspect they will just keep pushing anything helping actual gameplay to the next release. It's likes sc backers have come out in mass past week on reddit defending releases or dev speed. I really do not understand the dramatic up tick in my messages over the last week.
This has always been the case with SC. They're very good a getting art assets done (and redone, and polished), but when it comes to anything which requires some programming skill (networking, game mechanics, AI - ie. things which are required for gameplay) they seem completely unable to produce anything.