Not true.

Chrome: http://blog.chromium.org/2011/01/html-video-codec-support-in...

Opera: See an opinion piece at http://my.opera.com/haavard/blog/2011/01/13/openness

Chrome still supports H.264 and and there are no indications that Google is planning to change that in the near future.

Isn't the indication that Google said it will remove H.264? Have you seen Google go back on that statement?

Isn't this an issue of keeping the web open, rather than the cost of licenses?

Mozilla would need to be able to convey their H.264 licenses under open-source terms. That would effectively destroy most existing and future revenue streams associated with H.264 (as licensees could elect to use Mozilla's open-source license for free instead).

In other words, Mozilla would need to be able to buy the entire H.264 patent pool. Even at $300M/year, they're nowhere near that.