The dilemma Walliser and Porsche face is that the 911's entire positioning in the market revolves around being the only vehicle in its segment powered by a six-cylinder boxer engine mounted over the rear axle.

Achleitner said it was this irreplaceable peculiarity that allowed what at one point was a technologically obsolete sports car to successfully be transformed into the ultimate luxury sports car it is today. "The 911 wasn't always an icon," he said.

True, Porsche has been able to update the vehicle, for example to meet ever more stringent CO2 targets in Europe, while also growing sales. Enthusiasts deplored the move away from air cooled to water cooled but kept buying it. There was an outcry when Porsche shifted from naturally aspirated to turbocharged engines, and yet demand remains strong as ever.

But it feels as if Porsche has reached the end of credible changes. Historically, the 356 was replaced by the 911 in order to shift from four to a more powerful six-cylinder setup. Downsizing the engine and adding an electric booster to compensate for the lost output might be acceptable to some, but it would likely be a bridge too far for 911 enthusiasts.

It is these purists, who pay a huge sum for the 911's unique mix of attributes, that give the model its oversized profit margins and by extension bestow desirability to the rest of the product portfolio. Aware of their importance to the brand, Blume has said Porsche will build the 911 as long as the company is allowed.

By the time Achleitner stepped down from his post, he had changed his mind about the concept of an all-electric 911. Not only was it conceivable -- the tail-heavy feeling from the rear-mounted engine could be artificially reproduced, for example -- it was also preferable to eliminating a nameplate in which Porsche has invested so heavily over decades. But it will be up to Walliser to make this decision.

"What is the right path to take with electrification?" Walliser asked. "How does this look in the future and how do we actually achieve it given the process isn't something that can be completed over the next two or three years?"

An electric 911 must feel and handles like a pure-bred sports car rather than just boast impressive performance metrics for the classic straight-line sprint. "Anyone will be able to do that soon enough, that's is no longer a differentiator. But there are other ways to set oneself apart and our task will be distilling those typical Porsche attributes into an electrified vehicle," Walliser said.

Solving that conundrum will be his top priority should the 911 avoid the fate of the 356.