We are working on an instance cluster. Currently it is planned to be part of an update due to release after the Riders of Rohan expansion has shipped.
*sigh* Why? :/ I'm not fond of this method of supposedly giving us new content through the year. It feels like they're purposefully stringing things out to make it look like they're updating more frequently. To me that will be a faux update, one that should have come out with the new expansion.
So it looks like we're going to be in for the same problem as RoI. Hit level cap in a couple of weeks and then have to wait around. Lame.