They will have to. The entire team facility is now a crime scene, and though it's probably going to be a prefunctory investigation, given the witnesses, there will nonetheless be some sort of investigation. That will take at least a day, and completely disrupt preparations - never mind the emotional aspects.
The NFL will have to postpone - perhaps until Monday or Tuesday at least. To do otherwise would be... well, like the NFL.
The NFL postpones games for lots of stuff. And probably will this one. Notice the first part of that para was that there was speculation team officials were asking to postpone, then it declares as fat the league isn’t listening. How can there be a fact of somebody not listening to requests that are only speculated? Just bad reporting wanting to make the league look bad. Right now the league is probably just staying out of the way of investigators, waiting until they pause to get an estimate of how long the investigation will be so they know when to postpone to.