Slade is understood to have agreed to terms with another team with speculation suggesting he'll land at PremiAir Racing.
That leaves BRT with a spot to fill for the 2023 Supercars season, which could provide a lifeline for Holdsworth.
With Kiwi teenager Matt Payne guaranteed a drive at Grove Racing next season, and David Reynolds expected to re-sign, Holdsworth was expected to be on the move next season.
So far it has been unclear if he would pursue another full-time drive, or make a full-time career move into commercial real estate.
He had already spent the 2021 season on the sidelines, apart from winning the Bathurst 1000 with Chaz Mostert, ager losing his Tickford drive at the end of 2020.
While the door looks to be now closing at GR, the Slade move could create the perfect opportunity for Holdsworth to stay on the grid beyond the current campaign.
Motorsport.com understands Holdsworth is firmly in the frame for the BRT drive.
Other names that have been floated are former full-timers Fabian Coulthard and Zane Goddard, who have both made little secret of their desire to return to the grid.
Coulthard effectively replaced Holdsworth in Walkinshaw Andretti United's enduro line-up this year, while Goddard will drive for Tickford Racing at the Bathurst 1000 and has been heavily involved in the Gen3 testing programme.