We will have to wait at least 6 months to really start seeing if Mayer is able to grapple with the listless behemoth that is Yahoo. Most of that time will be her getting up to speed and laying her own foundation on where the company should go. So don't expect to see much in the surface for at least that long.
Digging further into the content of the story, in many ways this can be considered a valuable resource she has been building for many years.
People will follow a good mentor if there are special opportunities on offer. There are many people at Google and other places that are not satisfied with their options. To these people, money is not as satisfying as control and advancement. If Mayer is able to offer key people better options, many will be inclined to at least explore the idea.
Don't hang on to this idea that Yahoo is the place to suicide your career and/or company via acquisition. That's the old and current Yahoo. If Mayer is able to overcome that old inertia, then Yahoo could easily become a very hot place to be again. A good analogy is to think of an old, massive forest. It's all old trees that are half dead and centuries of undergrowth. A fire finally comes along and sweeps through. All of the undergrowth and dead trees are burned away. Now many young and vibrant plants can grow again, animals come back in abundance, and the whole forest ecosystem is better than ever. And please, hold off on the fucking criticisms of my version of forest ecology. It's an analogy.
So the point here is that if Mayer can start changing things finally, then there will be all kinds of interesting new things that people close to her could benefit from over the next few years.