Its very hard not to make a TL;DR: Boo hoo reply. So lets not do that.
I do think you're judging a bit to fast here. We all knew 2.6 wouldnt bring NiM. We now got the confirmation DF NiM is coming with the very NEXT patch. You really can't get it earlier than that.
Alltough 2.8 will be quite far away we really don't know much about it besides that we get another ops, DP NiM. Since bioware states it will be one of the biggest patches with the scope of RotHC you can assume new SM/HM opses too.
In short, I really don't see a shortage of opses. In the 1st half year we get 2 NiM opses and most likely 1 or 2 SM/HM opses.
There have been multiple posts, plenty from myself why that would be not only a bad move, but would induce rage if they released a new tier at the same time as Nightmare content. It would either have the same or better gear, or lesser gear. They would be smart to hold off for at least nine weeks before releasing the next big operation. Though it's bioware and they might shoot themselves in the foot.