That depends on how progress between lukaku and chelsea. I just read from gazetta if wants to sell him as soon as possible. Chelsea has been even decreasing lukaku's price so much. He is not priced almost a half from previous price.
Chelsea are a rich club but they must obey financial rules from UEFA. They are already in a watch list of UEFA and they will have to try to balance between transfer values from bought and sold players. With players who are receiving high salary and Chelsea don't have plan to use, they will try their best to sell those players and get some sort of money back. Lukaku is in their sale list, no doubt about it.
Chelsea are undoubtedly a rich team, but giving away talent is never a good thing. Of course if he has to raise cash it's another matter, if it were me I wouldn't easily give up a player like Lukaku who can make the difference in the opponents!
Lukaku has hinted he doesn't even want to stay at Chelsea. I think his performance in the Champions league final in which he was in the way of a goal bound ball, and also missed an opportunity to equalize still haunts him.
Perhaps with Inter still looking able to get to the final again, he could redeem himself.
Ac Milan and Al Hilal of Saudi Arabia also has shown interest in Lukaku but he insists on inter Milan. Inter sure gives him the comfort at this point of his career when he is nearing retirement and I feel it suits him his style now.
It is even better to play to a winning strategy from same manager, than to play to one who just got hired, has a team to build, players to offload and players to buy, without even a solid assurance of a final.