Dr Helmut Marko does not think either Ferrari or Red Bull will be able to beat Mercedes in 2019.
Earlier, it looked as though Ferrari had aced the 2019 rules change with its unique front wing concept.
In fact, Red Bull designer Adrian Newey thinks the new rules and tyres played right into Mercedes' hands.
"The working window of the tyres has played into Mercedes' hands perfectly," he is quoted by Auto Motor und Sport.
A Mercedes engineer confirmed: "The new tyres solved our biggest problem without us having to do too much for it."
And Newey thinks the situation is unlikely to change dramatically for the rest of the season.
"That will be difficult," he said.
"The whole concept of the car is designed so that the tyres do not get too hot. It's always difficult to break out of the concept."
Newey added: "The new front wings are in better harmony with the Mercedes concept."
He worries that Mercedes' dominance could also be locked in not just for 2020, but even for 2021.
"Their aero division is twice as big as ours, so even if only 50 per cent of their people focus on the current car and 2020, the rest can work on 2021."
One thing that would help for 2021, Newey said, is if the FIA holds back the new rules for as long as possible.
"The less time they have, the fairer it will be for all the teams," he said.
And so Dr Marko, a top Red Bull official, thinks Mercedes' continuing superiority in Monaco is a bad omen for the rest of the season.
"For the moment, you have to take it for granted that their dominance will last until the end of the season in Abu Dhabi," he told Kronen Zeitung newspaper.