But it emerged last week that Cosworth nonetheless completed an engine design for the new rules, even though it will not be built and raced this year.
America's premier open-wheel category also runs turbo V6 engines, and Cosworth chief executive Hal Reisiger said the marque is "committed" to finding an Indycar partner.
As for returning to F1, he told NBC Sports that Cosworth only abandoned its 2014 project because "there wasn't a team or teams plural that were willing to sponsor the development".
But Reisiger admitted that if current or subsequent talks with teams came to fruition, "Absolutely we would" want to return to formula one.
"I think that we provide a very cost effective solution for people to be on the grid," he said.
"We'd look forward to the right opportunity if we could find the right collaboration."