Yes these images are still disturbing to watch but in answer to your questions:
Bin Laden still on the loose? I doubt it, pretty sure the Yanks know exactly where he is and are happy to let him stay there.
Could it happen again? Yes, though perhaps not is such a dramatic or overt way, the Yanks prefer covert operations mostly. Lets not forget many Americans openly supported and funded the IRA for years, an organisation which indiscriminately killed innocent people, but hey, thats ok, it wasn't in their back yard! And thats just the tip of the iceberg.
It is reckoned that the USA has been involved in around 72 'wars' since the end of World War 2, mostly covertly, helping to supply terrorist with arms, overthrow governments, torturing suspects and holding suspects without trial or legal representation. Land of the free, I think not.
That is not to take away from the terrible loss of life in 9/11, merely to put a little perspective on it.