#SavedYouAClick
Some publicly-available Web statistics say that Mozilla Firefox has nearly fallen to just 2% of "the market" (of Web browsers), which means more sites won't bother supporting Firefox, testing with Firefox, or recognising anything based around Gecko for that matter.
"The loss of Google's payments to enforce a default search engine in Mozilla will be fatal to Firefox and Thunderbird due to Baker ensuring that [former Mozilla CEO] Mozilla became fully dependent on Google's money," an associate has noted. There are those looking at the financial statement of the company after election day layoffs (a lot of the media did not report Mozilla was about to lay off about 30% of staff) and deducing that Mozilla will run out of income in a matter of months.
If Mozilla dies some time soon, then someone will leverage the code to keep some community-run project (for Thunderbird also), but that does not mean compatibility with the "modern" Web will (or can) prevail. There are already many sites that refuse to work with Firefox or explicitly say Firefox isn't supported.
If the Web becomes just Chrome, then the Web isn't open at all.