Warne's retirement was fine IMO. Australia still won every test they played in the first year after he retired, so him staying around for another couple wouldn't have been that needed.
I am surprised Hussey didn't go for one more year though, and I too think he may end up regretting it. All it takes is a few months away from the game, something he hasn't had for years, and the hunger may return. Especially for a bloke I always imagined would have to be taken out of the Aussie side kicking and screaming.