So here is some wild speculation. Let's suppose McCain were to essentially cancel the convention, turning it into a charitable event where delegates donate blood, phone bank for the Red Cross, etc..
Theoretically, though McCain and Palin could still make a major speech from, say, Louisiana. President Bush and Vice President Cheney have already canceled their speeches -- so this isn't completely out of the question.
While the loss of press coverage might immediately appear to be a negative, it might not be the worst thing in the world -- especially in a year when McCain is seeking to distance himself from the Republican brand.
In addition -- and maybe more importantly -- this could possibly allow McCain to postpone accepting the nomination. I'm not sure of the rules, but my understanding is that he is not under the public finance system until he accepts the nomination. And with Palin pick -- and money pouring in -- wouldn't this actually be a good thing for McCain ...