Rangers have recently stated they are under no pressure to sell players despite ongoing losses but some of the squad could attract offers in January which would leave the club with decisions to make.
Van Bronckhorst said: "It's a difficult one. As a coach I have had many transfer windows and it's hard to predict what will happen, because anything can happen.
"The most important thing is to be prepared for whatever comes and that's where all the work will have to be done between now and when the transfer window opens.
"We will see. It can go either way but hopefully at the end of the window we have a better squad than when the transfer window opens."
He added: "We are discussing what has to be done but so far nothing has been decided yet about bringing in some new players in defence."
One player whose future is uncertain is centre-back Connor Goldson, who is out of contract next summer.
Van Bronckhorst hopes to get some clarity soon from sporting director Ross Wilson.
"I spoke to Ross about it and he is still talking with his agent," the Rangers boss said. "So we have to wait.
"I saw reports he rejected an offer but that is untrue. They are still talking so hopefully we can have some more news in the coming weeks or months.
"I don't have a clue what will happen because I have only been here for a couple of weeks. Maybe when I talk to Connor myself in the coming days and weeks I have more of a view on that."
Meanwhile, Ryan Jack will return to the squad for Saturday's cinch Premiership clash with Dundee at Ibrox.
The midfielder has not featured yet under the new manager after playing twice last month following his return from calf surgery.
"Ryan will be in the squad," Van Bronckhorst said. "He had not played a lot of games in the last six or seven months. I know he is an important player and we want him back as soon as possible. But we know he has got to build up his minutes.
"Hopefully in the next few weeks I can give him some more minutes."