Marco Reus hopes Dortmund can hold on to the stars that make the club.
Hummels and Gundogan have a shadow of doubt cast on their future, and Reus wants that to come to an end.
And with Aubameyang already committed to the club, Reus hopes they can all do so.
Reus – who committed his future to the club with a four-year deal in 2015 – told Welt: “If the club wants [to keep Gundogan and Hummels], then they will see to that.
“If you want to be on top, you have to invest in the team. We as players want to go to the very top and the club also wants that. There is no doubt that we can keep these players and bring in other good players. I am relaxed about this.
“We as a team will again get back to the top and the Champions League but, economically, there would also be other ways.
“Auba is very important to us. Many people may think he is just about style, fancy cars and glitter. But he’s tremendously professional and he works very hard. He is a good example that people should not be assessed on face value.”