The Bluebirds have spent the summer very much focused on the recruitment side of things, following their step up into the Premier League.
They have bought well and remain in the market for further fresh faces. Added competition for places will, however, force those already on Cardiff's books to consider their futures.
Out of favour frontman Etien Velikonja is among those to have expressed a desire to move on in an effort to find regular football elsewhere.
Mackay says he has no offers on the table to consider at present, but will not be standing in the way of anyone who wants to head for the exits - be that on permanent deals before Monday's deadline or on loan agreements.
He told Wales Online: "It's okay to say you want to move, but people have got to want you.
"We will take a look at the outs as and when they come in.
"Beyond 2nd September we can always loan. Right now, we are not actively out there selling players."