Some of the Hammers high earners such as Freddie Kanoute, Lee Bowyer and Don Hutchison are sure to be put in the shop window before West Ham embark on their first season of football outside of the Premiership for 10 years.
"I don't think we will have the same squad of players here at the start of next season," said Brooking.
"There is now a £15m-plus gap and we have got to reduce our wage bill.
"That might mean halving it, but we still need a strong enough squad to cope with a 46-game season.
"I'm sure there will be plenty of speculation in the next few days but we've got to take that with a pinch of salt. We've got to be sensible and cautious.
"That's it for me now as far as the manager. Hopefully we will be able to speak to Glenn and he will be involved in how we move forward."