Dumbrell has contested the Dunlop Super2 Series to stay sharp for the last five years, and purchased a minority stake in Triple Eight in 2015.
Asked if he would be understanding if the team replaced him with Lowndes, Dumbrell said: “The team’s got to put the team first.
“So whatever they need to do to win the [drivers’] championship and teams’ championship, that's what they should do.
“Roland and I have done six one-year deals. There's a couple of times in the last two years where other main series drivers were potentially going step down and not have a drive and I was the first person to say that if the team needed to make that call, I'm fully supportive.”
Van Gisbergen’s 2018 partner is two-time Le Mans 24 Hours winner Earl Bamber, a factory Porsche driver, after Porsche date clashes ruled out his ’17 co-driver Matt Campbell.
Lowndes will be joined by Steven Richards in his Autobarn Commodore for a fifth Enduro Cup, having won Bathurst together in 2015.
Six-time Great Race winner Lowndes said Dane had given him no insight on which of the Red Bull Holden Racing Team pair he would join.
“Roland keeps a lot of things close to his chest, although he is keen for me to be part of the co-driving [team],” Lowndes said.
“Who it’s with and what the program is like, I’m not really sure.”
Series leader Dumbrell drives a Triple Eight-built Commodore in Super2
Dumbrell expects the mix of Supercars co-drivers to change over the coming seasons, with Lowndes entering the equation part of that.
“Lowndes is an icon of the sport, I remember growing up watching him race and that awesome era he had in the [HRT] Commodore,” Dumbrell said.
“It's obviously sad that he wont be racing full-time and clearly by far he's going to be the best co-driver there is and down pitlane.
“He's still winning races in the main series this year, so it's going to change the landscape.
“If you look over the next three or four years, there's probably going to be three or four more main series - top 10, top five - Supercars drivers go down to be co-drivers.
“That just resets the co-driver market, some people will win out of it and some people will lose.”