Although this article may give us pause to think how things would be different, thinking about all the things that wouldn't of happened it is interesting to note that just maybe the things that happened that day had to happen that day otherwise it never would of happened at all in any other time frame.
We could just speak about all the theories but I remember reading an article that a sunspot eruption (CME) entered our atmosphere at about the same time as the towers were hit, and a gravitational anomaly was also present in the area of the towers at that time also.

Discovered since by the electric universe model, there seems to be an electrical connection between these storms and the sun not to mention ground effects near by at the same time. We at the suspicious0bservers have taken to calling these storms: "Earth Spots" because of their electrical connection between the highs and lows. Today at SO, there was a discussion that the tower may have played a role as well, (electrically). could of turned out quite differently.
It's been bantered about that events like this are thought to be planned out according to planetary alignments, weather systems...and believe it or not...the number of the day itself by the creatures that plan these things.......
[IF it was planned...not saying it was or not].
Didn't Francis Bacon or someone like that help the British with a war ship battle planned to the day and a likely weather event?

Could be an interesting discussion.