Here is the Roadmap. Things are pretty much on track. I had a big ol' update just a couple of days ago and it went smoothly and improved speed a little bit.
i don't think there's a rule that the new version has to be released by a certain date, like Ubuntu has. "It's ready when it's ready." The same is true of Gershwin, but more developers have joined to help that along as well. I watched a "preview" of the new desktop from @RoboNuggie recently, and it definitely looks like it'll take some getting used to for those of us who are used to the classic MATE and Xfce desktops.
