Governors would appoint temporary senators and schedule special house elections. A worse scenario is where a very small number remain alive. While the self imposed rules define how large a quorum must be, there is no constitutional rule. This would be an interesting supreme court challenge to see if 3 hypothetical surviving house members could change the house quorum rules and then pass bills as a 3 person body.
Quorom is a majority of the members. If there there was 434 vacancies and 1 representative, they would meet quorum.
