I agree with you, as much as I would love some news on NG4 sooner. As you said, I would suspect we won't hear about NG4 until sometime in 2015 and then see a Spring 2016 release....that would be my best guess.
But, I have a suspicion that we might see Ni-Oh in the coming year, unless it was completely dropped. It has been in development for a long-time and TN did confirm progress was going well on it a year or two ago. This is what I am most curious and hopeful to hear about from TN sometime soon. I think it would be good for TN to have one more major IP to be honest along with NG and DOA.