However long is left to run on the loan agreement, I'm sure Palace could recall Esse at any time if they wanted to. It would be pretty unusual not to have a recall option. Clubs have them inserted in case of an injury crisis at the parent club etc.
Glasner won't pick Esse even if he comes straight back to training with Palace next Monday morning and leaves an apple on his desk. Johnson, Pino, and Guessand have struggled so badly but the club haven't recalled Esse, so Glasner plainly isn't having him.