Ever since, Ferrari have been touted as the most likely destination should the 65-year-old opt to remain in the sport.
Now, it appears that move is in serious doubt, with the designer of the RB17 hypercar preferring to remain in his home country.
Where will Adrian Newey go next?
Motorsport Italy report that "Newey will not be able to make his choice official before the end of September due to Red Bull constraints, but it is increasingly clear that the intended destination is not Maranello."
According to the Italian publication, the exit of long-time technical ace Enrico Cardile from Ferrari has not opened up a space for Newey, with the Scuderia looking for a lead figure who would attend the factory daily, something Newey "does not want to be involved in."
If not Ferrari, and the chance to design the team's first championship-winning car since 2008 as well as teaming up with Lewis Hamilton and Charles Leclerc, then who?
Cardile's new team, Aston Martin, have been in the running since rumours of Newey's Red Bull departure emerged, and team owner Lawrence Stroll recently treated the design guru to a tour of their facilities.
Motorsport Italy add that the the imminent exit of Aston Martin CEO Martin Whitmarsh could be beneficial to Stroll's pitch, as Newey and Whitmarsh's relationship remains strained after the former's "stormy" departure from McLaren in 2005.
Perhaps a return to the Woking team is also on the cards, who have been involved in the "quietest" negotiations with Newey so far.