I'm not sure why people care so much about a missed guestimate from 8 months ago. Its done when its done. Why does it matter? This probably isn't one of those things that you want rushed, so theres no point in getting butthurt over a missed expected finish date. Or would you rather we use a shoddy not complete forum software full of bugs and security holes.
If you think it will be done before the end of 2015, you are crazy. 2016 isn't looking too hot, either.
What makes you think that? Have you been beta testing it and seen the progress being made? What are you basing your guess on?