For those who came in late, the use of Mozilla's Firefox browser has become progressively niche, which means it has fewer users these days. There already are plenty of large entities, both public and private, whose websites lack proper support for Firefox.
But it could get worse as the US Web Design System (USWDS) standard for those who build the US government's many websites requires developers to support any browser above two per cent usage as observed by analytics.usa.gov." (Firefox's market share was 2.2 per cent, per the traffic for the previous ninety days.)
If the US government pulls support then the front-end dev community but also the corporate IT departments for whom some web devs work will stop supporting it. Many corporations do a lot of business with the government, and thus, whatever the government does from an IT standpoint is going to influence corporations.
Corporations will see cutting developer costs and delivery times as a plus and could lead to an extinction event for the Red Panda.