https://netmarketshare.com/browser-market-share.aspx?options...
Not much has changed in the past year, with Safari holding steady at around 19% and Chrome going from 60% to 63%. Firefox is baring holding on to its 5%.
So while it's concerning to see MS embrace the Chromium engine from the standpoint of adding fuel to the Google fire, I don't see this having any real effect in the near term on the browser market nor the development of new web technologies. Firefox is certainly right to promote its excellent Quantum-based browser these days, but honestly I only see Firefox as being relevant on Windows. On the Mac, Safari is an excellent browser and one I use personally as well as for web development, and iOS doesn't allow any engine other than WebKit to be used. And with Android, Google has the upper hand on that platform.
In summary, as much as I want to cheer for Firefox and the Gecko Quantum engine from a philosophical standpoint, the only real competition to Chrome and Chromium right now is Safari and Webkit. Let's just hope Apple continues to put adequate resources into the development of its browser and keeps pace with Chrome.