LIFE will now change.
How? My guesses:
1. Every society has to find a mix of freedom and security that it can live with. More freedom equals less security, and vice versa. America tends to lean towards the freedom side of this see-saw. Other nations seem to prefer more security, and less freedom. My guess is that in America the pendulum now will swing towards security and away from freedom, at least for a while. Example: national identity cards. Most European nations have them, we don't. That may change. Another, obvious example: better airport security measures. Perhaps profiling of passengers (a dirty word nowadays, that may be rehabilitated). Israel does this aggressively, and, to my knowledge, hasn't had an El-Al plane hijacked in 25 years.
2. A less welcoming society. Although the perps are not known at this time, the evidence revealed so far points to Muslim extremists. The US has very relaxed immigration laws, and even more relaxed visa requirements. It's nice to be nice, but it's disturbing when terrorists seem to be able to enter this country and move around in it freely. I suspect this will change.
3. "Guns. Lots of guns." I am not a gun-nut—don't own one, never have, probably never will—but it's obvious even to me that even a couple of people with guns on those airplanes could have prevented the World Trade Center tragedy, and maybe even have saved themselves and the other passengers. The terrorists are reported to have hijacked the planes with tiny home-made knives?!? That, I suggest, is absurd. How could we allow such a thing to happen? A gun beats a knife, every time. No, I'm not suggesting that we let passengers be armed, or even flight attendants—"All carry-on luggage must be under your seat or in the overhead compartment, or my next shot won't be just a warning!"—but the pilots should have a couple of weapons in a locked case in the pilots' cabin, and be trained in their use.
4. The pilots' cabin should be locked and sealed by default, and bulletproof. Why the hell wasn't this done thirty years ago, when hijackings started?
5. A stronger tilt towards Israel in Mideast politics. I don't see how the terrorists could have expected anything else. The Palestinians, whatever the merits of their cause, will get increasingly less sympathy from the US.
6. Increased mistrust, approaching bigotry, regarding Arabs and Muslims for at least the next generation. Fair or not, just or not, it's going to happen. The Oklahoma City bombing dealt a killing blow to the nascent right-wing militia movement when it happened, because media reports tied McVeigh to the militias. Probably wrongly, but it's a public attitude thing. Likewise, even though most Arabs and Muslims may not have approved of the Sept. 11 terrorist acts, if the perps turn out to be Mideast Muslim extremists, all Arabs and Muslims will be tarred with the same brush. Another example is the Haymarket Bombing, which helped to turn public opinion against Anarchists, to the point when the very word ceased to have a political meaning, and became almost synonymous with 'nut'.
These things I foresee. But history never works out the way you expect, does it? Wonder what will really happen...