The states would pick new electors. If all else failed, surely the Supreme Court would intervene and make sure that common sense prevailed here, and that the candidate would get all of his/her electoral votes that they were entitled to.
I disagree the Supreme Court would step in if a sufficient number of states simply lacked contigency plans to replace electors. It's supposed to go to the House, and that's where it would go. And if they valued their lives, much less their jobs, they'd be sure to overwhelmingly elect the victor decided on election night, regardless of party disparity.
Even if they didn't, someone would have to blow up the House of Representatives too before the Court would step in.
