Muammar Gaddafi is dead and very few people in the world will regret it. Like Saddam Hussain he was found hiding in a hole. Very appropriate.
Some may regret that he wasn't arrested and tried at the Hague, but it makes no practical difference. I suppose the same could be said for Richard III after the Battle of Bosworth Field.
Rebuilding some of these Arab states is going to be difficult, but there is at least plenty of oil money in Libya. Hasn't helped much in Iraq, though.