Marissa Mayer - Can She Revive Yahoo?

Marissa Mayer, is the new CEO of yahoo, former employee and first female employee of Google. Now the internet company is likely to focus on web technology and products. She also stated that her focus will be always end users, great technology and terrific talent.

Marissa Mayer also stated that she don't think that success is by any means guaranteed.
Is this statement reveals about 'Yahoo future'?