Youth products Joe Ralls and Ben Nugent, along with Filip Kiss, Etien Velikonja and Kadeem Harris, have made just 13 appearances between them this season for Mackay's table-topping side, but the former Watford boss says their opportunity will come.
"It's great to say - and it's the truth - that I don't have a member of my first-team squad right now who is not part of plans," he told Wales Online.
"They have had to bide their time and wait. But I can see the progress they are making. I see that every day in training and I have complete trust in them.
"They are the long-term future of our football club. But Joe, Ben, Kadeem, Etien and Filip must keep working hard and making progress.
"There is nobody here that I am telling they should go and try to find a match elsewhere."