Wilmots has warned his highly-rated stars that they must be playing regular club football to be considered for his Belgium squad for the World Cup next summer.
Tottenham midfielder Mousa Dembele has been linked with a move away from White Hart Lane in the face of fierce competition for places in the Spurs midfield.
Similarly, Arsenal's Vermaelen has struggled to displace Laurent Koscielny or Per Mertesacker from the Gunners back-line since returning from injury.
Wilmots told Sky Sports: "We first have to settle to problem that players play for their clubs. December and January will be important even though I have little impact on it."
De Bruyne's Chelsea teammate Eden Hazard even suggested his Stamford Bridge colleague leave the club - at least temporarily - in search of first-team football in January.
"We will be dependent on the choice of players, who have to play for their club to get match rhythm," Wilmots continued. "Otherwise life would be too good to be true.
"The rhythm of a couple of players that no longer play with two matches in five days that is immediately obvious.
"We have quality, but quality needs match rhythm. You need matches, minutes of play. If you don't play, and sit in the stands, it becomes difficult."