They're unlikely to do that as keeping Chromium source available helps them to ward off antitrust legislation. They can hold it up and say "See, look at all these competitors!" when in reality they're all just Googles agenda in different skins. Meanwhile they get to continue dictating the web standards to cater to their profit motives by maintaining dominance over the rendering engine space.

If you care about a free and open web, Firefox is the only morally correct choice. Anything else is just capitulating to Googles dominance over the ecosystem.

I've been happy to see a few webkit browsers on Mac recently (like SigmaOS). Hoping others follow suit since that team seems to be doing good work again