One issue is that building a browser take engineers, and that takes a lot of money. Mozilla makes its money from search partnerships; they make money every time

One issue is that building a browser take engineers, and that takes a lot of money. Mozilla makes its money from search partnerships; they make money every time someone uses default search. If less people are using Firefox, less people are using default search, which in turn means less revenue. This means fewer engineers. If they don't have enough engineers to maintain Firefox, the browser falls apart. I am skeptical that Firefox could be maintained by donations or volunteers when its competitors are backed by large companies. A response is that even if Firefox's share falls, that the absolute number of Firefox users continues to rise. ie that the total market is growing. In this case Mozilla would still be generating the revenue it needs to keep going. The author brushes this possibility off in the beginning of the article, saying that browsers are a thing of the past.