And how many people will use it, apart from outliers like people who post here? The vast majority of people use one of the Big Three: Firefox, Internet Exploder [no, that's not a typo ;)], and Chrome.

Furthermore, if the Big Three implement a DRM standard, then web pages that want to "protect their content" will simply use the DRM standard, and it won't matter that Joe's Really Cool Browser doesn't implement it; that browser simply won't be able to view the pages. A few outliers like us will rant and rave; anyone else who tries it will say "Joe's Really Cool Browser Sucks" and go back to using one of the Big Three.