"We can survivie a WMD...we will not survive the destruction or setting aside of the Constitution."That does depend on where and to what extent -- does it not?
Should either New York City or Washington DC take a huge hit, assumptively a number of amendments would at least be suspended during an "State of Emergency."
There are no major cities with enough emergency service workers and police to deal with the ensuing panic and massive casualities from an effective WMD attack. There are not even enough hospital beds.
Field hospitals would be the first order of business.