And the same reports say Rosberg's pay has been about doubled, with his EUR 55 million deal bringing him almost eye-to-eye with Briton Hamilton's big pay-packet.
"The balance in the team is more important than anything else," Wolff is quoted by Germany's Die Welt newspaper.
On the face of it, Hamilton and Rosberg have clashed personally in 2014, as they battle for the 2014 crown with the dominant W05 cars.
But Wolff indicated that he sees Mercedes' pairing as similarly competitive but far more harmonious than many other potential driving combinations.
"We have deliberately avoided saying just how long the contract is," he insisted.
"But in the best case scenario, we all stay together until the cows come home," Wolff smiled.
Rosberg is also happy to give the impression of relative harmony with Hamilton, despite his rival saying recently that Germany is not really his home race.
"The interviewer started it as a joke," Rosberg said on Wednesday, "and my teammate then played along. I have no problem with that.
"We have a healthy rivalry as we fight every single race weekend for the win. That is precisely the challenge I am involved in motor sport for."