They'll shut Strasburg down mid-September, as they say they will.
With all of the Tommy John surgery being done these days there's enough data on how best to bring a pitcher back to form. And limiting the number of innings the first full year back is pretty much proven. They won't waste his arm when they have so much more talent to back him up.

When they shut Strasburg down, John Lannan will come back up and pick up the slack. He's a $5M "6th starter" playing triple A because there's no room on the roster right now.