As a regular person, I really can't see a 40% decrease in size (of which I'm skeptical) for just jpeg images (not nearly the full "65% of the bytes on the web") being worth the huge switch-over costs. The ubiquity of jpeg is just too valuable.
I mean cost beyond just web development. As mentioned in the article, there is a massive range of consumer and non-consumer products which have adopted jpeg as a universal format.
So those devices just keep on using JPEG and thus bear no additional cost. Even if WebP is only used between Google and Chrome, it will be worth it for Google.
