I realize we are basically coming to the climax of what would be the books. But next season is going to go at a super accelerated pace compared to this, already fast paced, season.
With only 6 episodes left, realistically that means probably two full episodes will be all that is devoted to fighting the army of the dead. Maybe part of a third. Then a fluff episode in the middle where everyone reorganizes and takes stock of their losses. Then a couple episodes of everyone fighting Cercei. That will of course end with her going mad and ordering her soldiers to burn them all. Which will trigger Jaime and make him kill her, thus bringing his story arc full circle. Last 20 minutes of the series will be Jon and Denarius ordering new thrones to sit on and melting down the iron throne.
For them to finish off everything that is still going on, the pace has to be around that speedy. The big threat we've all been dreading for so long, in the form of the knight king, has to be given no more than two to two and a half episodes worth of time.
And yes, I realize the rumor is next years episodes will each be around 80 minutes long. So even two episodes would mean devoting more time to that single battle than most Hollywood movies made today.