The latest rumours suggest former Werder Bremen coach Thomas Schaaf is going to be installed as new Schalke coach going into 2014.
Keller, however, says scrutiny over his position is something he has had to deal with since the day he was appointed as Huub Stevens' replacement almost a year ago to the day.
"Five times already I've been practically out of a job, when you listen to public opinion," he said to Sport Bild magazine.
"Roberto Di Matteo, Armin Veh and Stefan Effenberg were all meant to replace me, but I've fought my way through.
"I have achieved plenty of objectives and I think I've taken my chance, but what happens in the winter is not up to me."
Schalke are set to release a statement regarding Keller's future following their final Bundesliga fixture of the year against Nurnberg on Saturday.
Already out of the DFB-Pokal and five points adrift of the top four, defeat in Bavaria could well see Keller relieved of his duties, in spite of reaching the last 16 of the Champions League, where the Royal Blues will face Real Madrid next year.