If it gains traction and people like the features it brings, whats to stop all the current major players in the Browser space from just copying it? This isn't exactly a social media site where no matter how much money is thrown into Facebook it comes out on top because of sheer number of users. This is completely dependent on attaching itself to a browser. I have to believe that they would eventually implement it into their browsers if it started making money or became very popular for Yahoo.
And the second thing, what happens when Apple decides that this thing is competing directly with Mobile Safari and kills it from its store (and surprise, the other two major players in the Browser space, Google and Microsoft, also own the app store Axis is trying to deploy to).
So the best outcome for this thing is to be just a moderate success, where the big 3 in browsers don't really have incentive/time/effort to implement directly into the browser.