Now-departed Renault COO Carlos Tavares delivering the keynote speech at the 2011 NY Auto Show while still head of Nissan Americas.

Just weeks after announcing to the world his interest as serving as the chief executive of General Motors or Ford, Carlos Tavares has handed in his keys to the executive washroom at France’s Renault.

While his comments about finding an alternative job in Detroit landed like a shockwave throughout the automotive world, Tavares’ departure from the Paris-based Renault is far less surprising, the only question being whether it was already in the works earlier this month or was the result of his candid comment.

For its part, the French maker issued a terse release noting that, “M. Carlos Tavares has mutually agreed with Renault to cease as of today his functions of Chief Operating Officer in order to pursue other personal projects.”

What those other projects might be will now become an object of intense speculation within automotive circles and the auto media alike.

The Renault release offered CEO Carlos Ghosn’s praise for the departing executive “for successfully contributing to the results of the company all along his career.” It also noted that Ghosn will temporarily add Chief Operating Officer of Renault to his long list of titles which already include CEO of both Renault and its Japanese ally Nissan Motor Co., as well as head of the global Renault-Nissan Alliance formed in 1999.

The executive shake-up helps explain the unexpected failure by CEO Ghosn to attend a major media event in suburban Los Angeles. Dubbed Nissan 360, it was used to showcase the Japanese maker’s products and technology and to reveal some of its plans for the future. Ghosn was originally supposed to make the announcement on Tuesday that Nissan would begin building its first fully autonomous vehicle by 2020. The maker’s global product chief Andy Palmer had to step in and deliver that news as part of the event’s keynote address.

(For more on Nissan’s autonomous vehicle plans, Click Here.)

Until recently, the Portugese-born Tavares was thought to have a good chance of eventually succeeding the slightly older Ghosn, or at least taking on one of his chief executive roles. Though Ghosn recently won reappointment, he has been giving signs he might like to reduce the challenges of having to oversee both companies, as well as their alliance operation, in the next few years.

But Tavares, who has been a Nissan director since June 2005, and the COO of Renault since May 2011, seemed to suggest that his days with the alliance might be limited when he dropped a bombshell during an interview with the Bloomberg news service on August 13th – his 55th birthday.

“We have a big leader and he is here to stay,” Tavares said, adding that he had “the energy and appetite for a number one position.”  Asked what he had in mind, the executive suggested, “My experience would be good for any car company,” then pointed Ford Motor Co. and its major cross-town rival. “Why not GM? I would be honored to lead a company like GM.”

The open speculation created immediate rumblings, with observers asking whether Tavares was either trying to speed up the succession process at Renault-Nissan or making it clear to the world he was out looking for a new job.

(Nissan hints at new design direction with concept due for Detroit debut next January. Click Here for more.)

For their part, spokespersons at both Detroit makers downplayed Tavares’ remarks, Ford global communications chief Ray Day noting there was “already a succession plan in place” for the company’s top spots as CEO Alan Mulally begins to set his departure in motion. As the number two Detroit maker’s own COO, Mark Fields is considered the likely successor.

General Motors has been less transparent about its plans once Chairman and CEO Dan Akerson steps down but is believed to be looking at a minimum five internal candidates. That includes Mark Reuss, president of the company’s North American core operation. Ed Whitacre, the CEO who took over shortly after GM emerged from bankruptcy in 2009, originally hoped Reuss, rather than Akerson, would be his own successor.

“Tavares may have increased his chances of landing the CEO at GM or Ford by leaving Renault now, and making headlines so everyone in the industry knows he’s available,” suggests John McElroy, automotive veteran and host of the Autoline:Detroit news program. “I don’t think he’s got a snowball’s chance at Ford, but at GM? Who knows? The upcoming GM CEO transition is a difficult one to figure out right now.”

Could there be other opportunities beyond Paris or Detroit? It’s likely the shake-up at Renault will have a lot of folks thinking. And there’s little doubt that Tavares – who ran Nissan Americas before returning to Paris in 2011 – has plenty of fans.

“He is the best up-and-coming [future] CEO in the auto industry,” said Tom LaSorda, the former president of Chrysler told the Wall Street Journal. “The guy can run any auto company in the industry.”