The Wales captain has been used sporadically during a difficult campaign for the Spanish champions, starting 29 of the 42 appearances he has made this season.
Speculation surrounding Bale's future has only been enhanced by his struggles in the capital as Manchester United have been heavily linked with a summer bid and former side Tottenham reportedly want him back.
Bale, who joined the club in 2013, was left out of the squad for Madrid's most recent La Liga matches against Villarreal and Real Sociedad and his agent Jonathan Barnett told Goal last week that it was "a shame" that his client is not playing.
Los Blancos welcome Real Betis to the Santiago Bernabeu on Sunday in their last match of 2018-19 already certain to finish in third place, sitting 18 points behind leaders Barcelona and eight behind Atletico Madrid.
Having been included in the squad for Sunday's encounter, Bale may make an appearance in front of the Madrid fans before the campaign comes to an end and it remains unclear if he will be back next term.
"Bale is going to be in the squad list tomorrow," Zidane told reporters on Saturday. "I'm not going to say if he will play or not. You will see tomorrow. Could it be his last game? I don't know. I can't say."
Madrid have been unable to put up a challenge for the Liga crown this term and crashed out of the Champions League and Copa del Rey early this season.
And the coach is eager to draw a close to a tumultuous year and begin preparations for 2019-20.
"I would say to the fans it was a difficult season, but let's think about next season, we are willing to start the next season with work and to make the fans be proud of us," he added.