I am not so sure you can speak of a comeback here, for the simple reason that for a comeback you first have to have been on a sidetrack. Although in public appearances Larry was not visible for a number of years, he has never been out of sight inside the company, for example by approving every single new hired employee in the company. Also Apple was facing a disaster when Steve Jobs was coming back, while Google has shown financial stability and growth in its full history.

What you can say however is that Google is now in its third phase, after its startup phase where it was fast gaining interest of a huge user base and initial investors through technological inventions and a second phase of monetizing and creating a stable money generating platform. Larry knew precisely when to take over control again: at the moment when sustained growth through conventional business practices had ended and innovation level was declining.

CEO is after all just a job title and with the amount of shares they held, Larry and Sergey could practically have get rid of Eric Schmidt any time they wanted but there would have been no way Eric could have kicked those two out of the company.