Millen has led Palace since Ian Holloway's departure last month, but revealed on Thursday that the club are in talks with a potential replacement, with former Stoke City manager Tony Pulis reportedly set to be appointed imminently.
"I spoke to the chairman on Tuesday and saw the chief exec this morning. They are in discussions, but I don't know who with," Millen stated.
"I've been told to get the squad prepared. My desk has been moved into a different office - I'm a bit nearer the door now!
"It looks like maybe this could be my last game in charge. I'm not looking at that. I'm just focusing on the job in hand.
"It's not right to talk about staffing issues until a new man does come in. He will assess what's here and see if he's happy with us.
"We need someone with Premier League experience because a lot of us are very new to this level."
Millen went on to call on Palace's players to remain concentrated on the task in hand at the KC Stadium, adding that he feels privileged to have temporarily managed the club he supports.
"We've got the squad prepared to travel tomorrow for the game at Hull. We are looking forward to the game," he added.
"It's not easy with the speculation. It's a massive game Saturday and we've got to try and stay focused.
"It's been an honour to take charge. I've supported Palace all my life. I'm proud of the response the players gave me.
"Ultimately though we need to start winning football matches and that's what we are aiming to do Saturday."
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