Carlos Ghosn, perhaps the most powerful man in the global auto industry, is stepping down from his role as CEO of Nissan Motor Co. (NSANY) as French rival PSA Peugeot (PEUGF)  accelerates plans to buy the European operations of General Motors (GM - Get Report) .

In what could be the most significant development in European car marking for several decades, Ghosn will relinquish executive control of Nissan, a role he has held for more than 16 years, in favor of a focus on alliance partner Renault SA (RNLSY)

"This planned change will also allow me to devote more time and energy to managing the strategic and operational evolution and expansion of the Alliance and ensuring that all its members benefit from the competitive advantages that its scale will deliver," Ghosn said Thursday. "I am committed to supporting the Alliance as it evolves and expands, and will continue to serve each member of the Alliance wherever and whenever necessary."

Ghosn, 62, will remain chairman of all three groups in the alliance -- Nissan, Renault SA and Mitsubishi Motors -- but will now focus his considerable energies on the French portion of the complex three-company group.

The timing of the decision, which has been an ongoing subject of industry speculation for several years, is interesting in that in comes shortly after Renault's domestic rival looks set to strengthen its European market share with the purchase of GM's struggling Opel and Vauxhall divisions that would create the region's second-biggest automaker behind Volkswagen AG  (VLKAY) and ahead of Renault. 

It could also set up a fascinating head-to-head competition between Ghosn and his former protege, Carlos Tavares, who has somehow steered Peugeot into a profit after three years at the helm, promised the first dividend in at least six years and plans to improve operating margins while expanding sales.

Reuters reported earlier this week that Tavares is targeting a 16% increase in sales -- to 5 million units -- from a combined Peugeot-Opel and savings of around €2 billion over the next five years. 

Renault is also improving its European tiremark, as its top-selling SUVs boosted market share last year and drove the group's net profit 38% higher to €3.3 billion. Like Peugeot, it also wants to boost operating margins over the next five years and hold costs steady while it invests in new technologies such as electric and self-driving vehicles.

What that means for the 39,000-strong Opel workforce -- or indeed the 4,500 jobs at Britain's Ellesmere Port -- remains to be seen. 

Both men, in fact, have had meetings with U.K. Prime Minister Theresa May, who has been desperate to protect British jobs in the automotive sector following the country's decision to leave the European Union last year.

May is reported to have offered a "sweetheart" deal to Ghosn that would prevent him from moving a key Nissan plant in Sunderland, which assembles more than 600,000 cars a year, to the Continent and said she and Tavares has the "shared goal" of strengthening the country's automotive supply chain, according to a government spokesman.

The fate of British jobs, however, may not be top of the priority list of either Ghosn or Tavares as they prepare for what could be an intense battle for European customers in the coming years.

Fiat Chrysler (FCAU - Get Report)  , the heretofore forgotten name in the region, lead European rivals with a 15% gain in vehicle registrations in January and a 30 basis point market share increase to 7.1%, according to figures published last week by the European Automobile Manufacturers Association. 

PSA Group, Europe's second largest carmaker and owner of the Peugeot and Citroen brands, lagged its European rivals with volumes growing 6.8% and its market share slipping 30 basis points to 10.3%. Europe's largest car maker by revenue and volume, Volkswagen, posted volume growth of 10.3% during the recent month and held its market share steady at 24.1%. Renault held its market share steady at 9.1%.