I’m not under the impression it would unseat PNG anytime soon, but “we have a current standard” isn’t a good argument against it. As images get higher and higher quality, it’s going to increase the total size of images. And we are going to hit a point where it matters.
This sounds so much like the misquoted “640K ought to be enough for anybody” that I honestly can’t take it seriously. There’s a reason new algorithms, formats and hardware are developed and released, because they improve upon the previous and generally improve things.