The essential problem here is that a web browser is nothing without content, and much of the most popular content on the web is found through Google, a company who grows closer every day to locking down a vertical monopoly. Firefox would have to be ten times as good as Chrome to even be on equal footing, and while it does have some marginal advantages, nothing is enough of a deal breaker that I would stop visiting YouTube just to avoid using Chrome [1]. Firefox really was that much better than IE6, but Firefox isn't competing with abandonware this time around.
Mozilla needs to stimulate the creation and viewing of content outside of Google-owned walled gardens. Pocket Recommendations were an obvious attempt at this; just make sure all the recommended articles actually open correctly in Firefox. This was probably also the biggest reason why they bent over so far backwards to accommodate NetFlix, who would have been happy to make sure Firefox worked correctly just to avoid being vertically integrated to death by Chrome and Google Play Movies/TV.
The relationship between Steam and Linux comes to mind. Funny how Linux became a viable gaming platform right after Microsoft announced the Windows Store.
[1]: This will, of course, change once uBlock Origin stops working.