FIA president Jean Todt says it's very unlikely F1 will attract new manufacturers in 2021, with efforts now focused on retaining the sport's current pool of four engine suppliers.
Initially, the whole premise supporting a major overhaul of F1's engine regulations was to lure in new manufacturers or independent engine suppliers with a cheaper, less sophisticated power unit from 2021.
Interest has been limited however, with just one manufacturer - believed to be Porsche, according to Motorsport.com - potentially putting itself on the ranks to join F1 before dismissing the opportunity.
"There was some demonstration of interest from one, who said to us we are not in a situation to commit for 2021 but, what is very important for us, is to know exactly what will be the regulations, because there could be a strong interest in the future," Todt told Motorsport.com.
While F1's engine of the future was expected to retain a significant hybrid componet, it was also anticipated that the format would abandon the current controversial and costly MGU-H element.
However, F1's manufacturers - Mercedes, Ferrari, Renault and Honda - agreed in the past months to carry on in 2021 with the MGU-H, because producing a whole new power unit, while continuing to develop their current engines, entailed excessive costs.
In the absence of new manufacture interest, Todt underlines the necessity to keep F1's current car manufacturers happy, and in the sport.
"My priority is to make sure that we keep them four," he said.
"I always said it would be very unfair to the four engaged to say, ‘okay, we want to attract a new one so let’s change everything’.
"But what about them? What about all the investment they have been doing for years and we say, we change completely the regulations because we may have one or two coming?
"That is one of the reasons why it was not a revolution on the engine regulations. Now if we can secure those four for me that would be a great achievement."