Actually senior citizens represent a small part of the consumer economy as their spending dramatically decreases in retirement and certainly as they get into 70's-90's, which is why advertisers do not consider them "in the demo" (they do spend disproportionately on cruises, but that's an anomaly).
However, the spending on senior citizens for healthcare, housing, hospice is enormous. Losing the current two million seniors a year doesn't impact the economy as their spending on consumer goods and housing is reduced by that age, hence a 20-30% increase in senior deaths would not have a devastating economic impact (actually some would be netted out against the cost of their extended healthcare costs). The senior living and drug stocks would get crushed though.
If you spent years around insurance actuaries like I have these conversations of risk, death rates, and trade offs are as common as debating the value of FP+.
Everybody dies, it's just about probability tables and timing.