Most people interpret, and I think rightly so, that what he means by "need up until Episode 14" is to complete all the story setup for the grand finale. He did the same thing with AL where Ep 6 completed all the setup choices and Eps 7 & 8 were the finale and epilogue respectively where our choices came home to roost.
I also don't think he's going to just do a 2 episode final season for Steam and there was another part to that Q&A answer where he said something along the lines of how S4 wouldn't a "regular" or "normal" season, or whatever word he used. I look at that as him hinting at what I just said, that Eps 13 & 14 are the regular episodes with choices, minigames, parties, etc, but then Eps 15 & 16 play out more linear as you play through the ending and the consequences of your choices. That would qualify as a non-typical season in my books.
But gains a new one with the friends she makes at college