Don't think it'll go the way you think it will. I don't think people will go out with a whimper. I think Those that have talent will jump ship. But again i also think perhaps sc&p will even succeed, but with different clients. They are doing what clients want, easy sells, nothing too edgy. Don was always the edgy creative guy who pushed the clients ideas back until they accepted his. He was good at his work, but more than anything he was persuasive at getting them to even buy it. Like he said, when you don't like what people are saying , change the conversation.
So perhaps peggy is unfulfilled at sc&p but that doesn't mean she couldn't go somewhere new, she was up there at the old agency with ted, she was doing great, and proved herself capable of good ideas. So she could keep doing that. Ginsberg was established in S5 as an amazing creative guy like don. Rizzo is legit too. They are all great, and they can get work elsewhere. The people who would have trouble are those married to the job. But even don doesn't seem married to SC&P, but married to the lifestyle that gave him. His a man who gets off on making people think what he thinks. He's good at talking his way out and into things.
I see him starting his own agency or atleast with pete/rizzo, or going back to work at sc&p and still being successful. He's already changing his lifestyle and the choices he makes, so i don't see how he couldn't go back to the agency and wow the clients again and again like he used to. I mean going off the first pitch this season, he's definitely still got the ability to do it.