3) Who’s replacing him?
Lucas Giolito has a bright future, but he’s at least a full year away from the big leagues. Jordan Zimmermann will likely sign elsewhere, leaving Washington with a rotation of Scherzer, Strasburg, Joe Ross, Gio Gonzalez, and possibly Tanner Roark.
Gonzalez is beginning to decline, and Roark is a number-five starter. Ross has a ton of upside, but he’s not ready to be a number-two starter on a contender. If the Nationals want to trade Strasburg but keep their postseason aspirations, they will have to sign a mid-tier free-agent starter. Whoever that pitcher is, he will not be as good as Strasburg, and will likely cost just as much.