The three players have been sidelined with respective thigh, head and knee injuries in recent weeks, but Ancelotti is expecting all of them to recover in the near future.
Following the La Liga clash at Almeria on Friday, Real will travel to Morocco to take part in the Club World Cup.
Real will face either Cruz Azul or Western Sydney Wanderers in the semi-final on Tuesday, ahead of a potential showpiece appearance on December 20.
"Modric's recovery is going well and he will be back with the team in January," he said.
"We hope that James will be training next Thursday and will be available for the final [should Real qualify].
"Khedira will travel to Morocco. He will certainly be available for the final."
But Ancelotti has warned of potential tricky opponents to come before deflecting questions about possible transfer activity once the window re-opens in January.
"The Champions League second place teams are more competitive than last year. [Such as] Juventus, PSG..." he said.
"Transfers? We will take a decision after Christmas. It depends on the injured players."
