This is kind of a moot point. If you read the article carefully, you'll notice that Yahoo will be bringing "a new, re-imagined Yahoo search experience to Firefox users in the U.S"
I wonder if or how Yahoo's "re-imagined" search experience will be affected for non-Firefox users.
UPDATE: Yahoo's press release says their "clean, modern, and immersive search experience that will launch first to Firefox’s U.S. users in December and then to all Yahoo users in early 2015."