Van Holsbeeck still expects Lukaku to leave, with Chelsea clear favourites for the youngster, but warns there's a long way to go in negotiations.
"We all need a bit of patience," he said.
"The transfer of Lukaku will depend on several things. Only when Romelu has made a decision will we have more news.
"We are negotiating with several big clubs Lukaku. I can say, whoever buys him will not be loaning him back to us."