Fleck, 17, became one of the hottest prospects in Scotland last term after being given a run of games by manager Walter Smith.
With Rangers having trimmed their squad, the attacking midfielder is expected to feature even more in 2009-10.
Assistant boss McCoist said: "We're expecting things from John, of course, but it's a funny situation.
"When he broke into the side, we always knew it wasn't going to be an overnight thing. He's a young, young boy in a game nowadays where young boys don't really break through and make an impact like they used to.
"John was always going to be, from our point of view, a prospect for the long term. But in the last week or so at training, he does look a lot more self-assured and confident.
"He seems to be building himself up but I don't want to put any more pressure on him by saying he's going to do this or that.
"I just hope there's a natural progression in his play and that he's grown up, if you like, in his understanding of the game.
That's all we can ask for.
"There's not going to be a dramatic improvement, I wouldn't have thought, but as long as we can see some improvement then that will be good."