John scored a point-saving penalty for the reserves against Charlton on Tuesday evening, but his first team chances have become fewer and further between in recent seasons.
But Glenn says there is life beyond his playing days, explaining: "John Moncur is very experienced and perhaps he is now in his last season as a professional player.
"He has been in this situation twice with West Ham now and I need the John Moncurs around the squad.
"I have always said that if he really wanted to get his head down and concentrate he would make a brilliant coach.
"His knowledge of football is terrific. He has got a very good opinion not only of his position in midfield but everyone else's as well.
"He thinks about what should be happening at certain times in a game.
"That is for the future, but if he shows any inclination to want to coach I would encourage him."