Wales international Bale has started only one of Madrid's last four games and has become a target of barracking from frustrated fans.
Reports this week have claimed the Madrid hierarchy see him as "a problem" because his refusal to consider leaving could block moves for targets including Chelsea's Eden Hazard and Manchester United's Paul Pogba.
Bale's agent, Jonathan Barnett, this week told ESPN FC that "nothing has changed," with the player under contract until 2022.
And there appears to be no obvious destination for the 29-year-old, with sources telling ESPN FC that Manchester United have no plans to target him.
Asked at a news conference ahead of Thursday's game at Getafe whether Bale would have to leave for Hazard to arrive, Zidane said: "No. But we are 25 players, so if you buy players, some might leave.
"That is normal in a squad. There will be changes, but that happens in all teams."
"Courtois is ready, he has trained with us, so he is available for the coach and the team," Zidane said.
"I will not say who will play tomorrow, but you will see who plays over the last five games. Then [in the summer] anything can happen.
"I will not tell you what I want. Sometimes I want things but they do not happen, just the opposite. The keepers all have contracts. This is not the moment to talk about this, but next year it will all be very clear."
With rivals Barcelona set to wrap up an eighth La Liga title in the last 11 seasons, Zidane was asked what Madrid had to do to end their dominant run.
"Barca have been doing well lately, and you must congratulate them," he said. "In history, Real Madrid have many more La Liga titles but Barca have been better lately and next year we must change that.
"We want to start La Liga very well next year as, if not, it will be difficult again. For me and for the players, La Liga must be the primary objective, for sure."