Actually there were changes made after 9/11 because the networks did not feel they could go on with the scheduled awards in light of the HUGE tragedy. They had a lot more time to make the change and adjust schedules.
In light of this tragedy, and the fact that this is not on the scale of 9/11, I would not expect them to cancel but rather to do a tribute or statement during the awards. These types of tragedies are becoming so common these days that, sadly, we would be cancelling and postponing everything and we cannot give those who wish us ill the satisfaction of knowing that they have changed our world to that degree. It is hard to go on, but we have to be strong.
"Life is a lesson in humility"