If they're not working, they're not producing wealth, they're living off a pension or savings, and in either case that money doesn't evaporate, it goes to someone else who will spend it. Buying a widget doesn't create a widget -- someone building it does.
The labor force not working is what's going to cause the decline in GDP, not retired people dying.
I'm not saying it's not bad, it's obviously horrific, but I think the deaths themselves will not overly impact the economy.
