Fire and police strike?

So here's a frightening scenario: you decide to throw a four day party for thousands of people. That particular party will draw hundreds of thousands of protestors ranging from peaceful marchers to anarchists. The general climate is one of fear (of dissent as much as terrorism). In control of the city where the protest will be held is a Republican mayor determined to keep order in the face of all of those pesky people who thought they had constitutionally protected rights of free speech and assembly. Now, say this same mayor is at odds with 8,000 firefighters and 23,000 police who are threatening wildcat strikes during this not-so-little shindig. So what happens if two-thirds of the people the mayor counts on to keep the protestors under wraps suddenly don't go to work? Who does the mayor call?

Interesting question. The possibility of a strike has made the media, but I haven't seen coverage of backup plans should it happen. Anyone care to venture 1968 as an example of what might happen?