Watch this. He specifically mentions the skill and rune design team have the luxury of working on those systems. Meaning the main thing holding up the game right now is not Attributes, skills, or rune system. It's 100% polish, bugs, and online services. They just have the luxury of extra time with those design teams.
So while everyone oohs and aahs about skill reworks, they probably finished months ago.
The real sign of release is online service, polish, and bug fixing. Meaning that the bnet stress test and how well that goes is the main indicator. Not uniques, skill systems etc, they just have the luxury of working longer on them, its not the holdup.