Norwich had a £5million bid for the Hoops striker thrown out last week, but they could return to the table.
Brown has seen former Hibs team-mate Steven Fletcher forge a successful career with Sunderland, but he hopes Hooper will not follow suit south of the border.
He said: "The last I saw Gary was on Saturday. But I spoke to him on Sunday and he was on his way down the M6, so I wished him all the best. It's each to their own, but Gary is settled, he is enjoying it and he's playing brilliantly.
"You can understand why teams like Norwich are looking at him and it's only a matter of time before someone else puts another bid in for him. We want to keep him. We want to keep the strongest team possible, but, at the end of the day, some players come and some go.
"I just hope he's one who stays. It's huge as we have a big game against Juventus, too. As it stands, the club has rejected the bid.
"Everyone puts Gary down just because he plays in Scotland for Celtic. If he was doing this week-in, week-out in the Premiership, he'd be worth £15m or £20m.
"It's hard the way people see Scottish players, but we're in the Champions League and doing better than a lot of the clubs down there.
"Steven has scored a lot of goals in the Premiership and his confidence is getting better. He's improving and it's good for him. If it happens for Gary, I wish him all the best, but I hope he stays."