From what I know there are no plans to add this resolution.
Since most people would use it for stabilizing in post production anyways, you can simply go with the active stabilized 1080p.
Since the 1080p 60fps on the X3000 has a higher bitrate than the competing products, you can even export the video as 1440p and there is close to no difference between that and native 1440p recorded on other cameras.
Except for the stabilization process, the other thing you could do in 2.7K, was to zoom your shot, without loosing quality.
You could do the shot in 2.7K in wide angle (using a large portion of the sensor, thus better quality) and then in post, you could zoom in with the final result being practically of the same quality as if you shot at 1080p at the first place.
Now if you zoom in posta with a footage of 1080p the picture quality will degrade significally.