A good run? He just got beaten to a pulp by a Mexican! Then when he fought Randy, who is much much older and had a broken arm for the best part of the fight, he struggled. He is a wrestler, pure and simple. It's what he does best.
With the right offer, Vince could persuade him to come back I'm sure.
Wrestlemania 27 card: Brock vs. Taker for WHC, Barrett vs. Cena vs. Orton (WWE Title) and HHH & Nexus vs Sheamus would be class.