The 22-year old winger has been linked with Blackburn Rovers and Leeds United but McNamara says that the Terrors do not necessarily need to sell at this point like they did with Johnny Russell to Derby County earlier this summer.
"It's part and parcel (given the) player's ability,” said McNamara of interest in Mackay-Steven.
"Johnny Russell left there going into his last year, which we had to do. We couldn't afford not to. That's the nature of the business. The club has a selling point if players aren't going to sign new contracts.
"Fortunately Gary has two years to go so it puts us in a stronger position.
"Speculation means he is doing things properly and doing well, so long may it continue."