Sanders' plan is more long-term than to just get elected president and try to change everything. He wants to create a massive socialist movement of some sort, to try and fix the problems before they get bad enough that we need a real revolution. With any luck, his movement will last much longer than he lives.
Keep in mind that's just based off my analasys as a leftie. But what I hear when he says "political revolution" is "I will not live to see these problems fixed, but I'm gonna get the ball rolling."