He has 13 2/3 innings left until he reaches 180 innings with 29 games left to go. Even if they go to a 6 man rotation and skip him once that would be 3 more starts, which likely would but him over unless he is going to throw 4 innings before the playoffs start.
So, with 3 starts, he'll hit his limit with 2 of them, and basically be one start beyond that limit. Each playoff start would be an additional start beyond. I could easily imagine them having such a comfortable lead on washington that they could easily rest him another time and skip his last start, too.
I can't imagine the "180 innings" by Andrews is more than a guesstimate, though. Why did he choose 180 versus 170 versus 160 versus 190? 180 is safe and no-problem, but 186 is going to wreck his arm? Andrews has this pinned down to the nearest 3% precision? I don't think so.
The other thing is that if he has a subsequent injury, will we blame it on the extra six or 12 innings? I suppose if in inning 183 his arm breaks like Dave Dravecky, or he has an obvious pop or tear like Kerry Wood or something, it will be easy to say "that extra 6 or 12 innings did him in." But if next year August he has an injury, or in 2017 we notice that his velocity isn't quite what it used to be, will we then blame it on 3% overload in 2015?