I'm glad to see Legard going (though part of me feels a little sorry for the guy really, I'd probably be feeling pretty sorry for myself if I was him right now).
That said, while I like Coultard, I don't feel that him and Brundle are quite the right team. Brundle's style has always been quite methodical and he offers his amazing insight as a former driver. I've also thought it's better that the other commentator perhaps be somebody who isn't a driver, so they don't clash, but instead has great knowledge and enthusiasm.
In a way, you need somebody like Brundle, then somebody who is a little louder and get's a bit excited. Coultard isn't that, infact he's probably quieter than Brundle.
I know most people weren't keen on him, but I wouldn't have minded seeing James Allen back. If you read his blog he is really up on things... I think he just always struggled because he was Murray's replacement, but he wasn't Murray. With hindsight now, he wasn't so bad.
The 5live team also are good, especially now they are on the practice sessions, but I think they've had that option available for a long time and have never moved on bringing one of the team over to television.