The 9/11 story needs to be mandatory as a lesson for schools in future generations. When only Pearl Harbor can equate the impact of 9/11, it is time to put it in the history books. "We will never forget" was a battlecry for a number of years after 9/11, and we need to keep that promise.
I think it should be in the textbooks along with all other major historical events. I think a teacher would get in massive trouble if they decided that WWII shouldn't be talked about and decided not to teach it and I think the same things should happen with September 11th.
I think this is a very good idea, honestly. The next generations of young students need to know their history and there is no doubt that September 11, 2001 will go down as one of the most tragic and yet history making day in the history of the United States.
The events of 9/11 will not be forgotten even if they are not covered extensively in schools, particularly due to their recent nature. While this is the last generation of high schoolers who likely remember 9/11 occurring, everyone alive now either remembers or has parents who remember the events of that tragic day and it is unlikely to be forgotten any time soon.