This seems more like a question geared to the Simple Questions thread, but I will try and turn this into a discussion.
To answer your question about if we know when or if they episodes will air; we have no idea or confirmation on anything for the sort.
As for where is Plasma, maybe they won't even have Plasma? Maybe they are waiting till the Conference to have Plasma interfere like they did when the player in the games was challenging the Elite Four?
There are plenty of possibilities of what they could do with the Plasma episodes. They could rework the storyline, show them in another venue such as Dragonspiral Tower or else where. Or Plasma may not even appear altogether. They may have new villains and BW2 and have TR rival them instead of Plasma. At this point it is hard to tell since the delay has been over a year, so anything could happen at this point.