One of the best ways to earn money with Flash games is by making sponsorship deals. The developer puts the sponsor's logo and a link to their site in the game and lets the game spread around the web. The sponsor gains money from the ads and the extra traffic to their website. Alternatively, they site-lock their game to their website (usually for a short period of time) so that people who want to play the game go to their website. It's true that one can remove the site-lock with some effort by decompiling the swf, but it's usually not done as it's not worth the effort and not legitimate. Another significant part of the Flash business model is to put advertisements in-game. There are other ways of earning money with Flash games, but from what I know, these two are the most prevalent ones.
Since HTML5 is necessarily open source, it makes me wonder if this model would still work for HTML5. Even if you obfuscate your js, it's much easier than Flash to copy the game, so maybe it's worth the effort for someone to copy the game to their (illegitimate) site. If you add your sponsor's logo and link or advertisements, it might be worth the effort to remove them for their site, something that I think is much harder to do with Flash games. Perhaps even the illegitimate site could claim that their site is better because there are no in-game ads. There's still the legitimacy barrier, but I wonder if it's strong enough.
Let's put aside all game development technical restrictions regarding HTML5 for this question (suppose for a moment that HTML5 works just as well as Flash for games). I have two very similar (pair of) questions. The first is, would the Flash business model work with HTML5? What changes to it would be helpful for HTML5 games? The second question is, what about the big picture for HTML5 games? Is adapting the Flash model really the best solution, or is there a better model for the HTML5 games world to "turn"?