In the new role, her not-small task is to reposition Yahoo by tweaking its Panama ad system to deliver more customers to advertisers and more profit to publishers. Amid growing nervousness about Google's dominance, Decker has a real opportunity to succeed. If she does, she's a shoo-in to follow Terry Semel as Yahoo's next CEO.Apparently, lots of big advertisers are not happy with Panama. AdSense continues to outpace Yahoo's advertising system, and as for being a shoo-in as Yahoo's next CEO? Not gonna happen.