Article is terrible. There is and HAS always been procedures. For House of Representatives: "When vacancies happen in the Representation from any State, the Executive Authority thereof shall issue Writs of Election to fill such Vacancies." Article I, Section 2, Clause 4. In English, you HAVE to hold a special election. Rules for that is by state. For Senate, governor appoints the interim senator.
Article author failed civics 101. The special election requirement is a feature, not a problem. As long as one Rep survives, House of Representatives can function. Senators can be refilled by their governors. So no big problem there. Changing this situation would require a Constitutional amendment.
In my opinion, it would be a very bad idea to let governors pick both Senators and Reps during a mass casualty event. Apparently the rule that did pass is a law requiring states to hold expedited special elections within 49 days, if more than 100 congressional seats were vacant.
So in other words, we do actually have procedures in place for mass casualty events in Congress. It is intentionally not fast or efficient. Nor does it need to be. In an emergency, Executive handles the day to day stuff of running all the government agencies. Presidential secession rules were worked out in the Cold War. Article just failed to make it clear or concise. Because why point out reality when you can write sensationalist dreck for clicks.
Short story long, we're fine.
