I have always thought if a disaster, whether it be man made or natural, were to hit on a large enough scale to make a national (or worldwide) impact, it will be one that we don't see coming.
All of the sensationalized disasters (2000, 2012, etc...) usually involve little reality and allow for massive preparation on the part of those that can ease the impact.
The stuff we don't see coming and isn't in the news is what will be the major events. It will be on us before we know it and before most can prepare for it.
What will that be? Who know's, like I said, it will hit before it is publicized. Maybe war, maybe viral, maybe natural? That is why it pays be be at a certain level of preparedness regardless of what the news reports. It's better to have it if / when you need it instead of waiting until you need it and can't get it. Of course, being paranoid goes to far, be "prepared" is just right.
Let Hollywood make movies, they are fun to watch but the epidemic, meteor, earthquake, weapon, etc... that causes the real thing won't be the one they are making movies about.