He could also make a big contribution before then to the club's survival in the Premiership, which would be worth around £20m in total.
But that is not Dowie's only concern. He said: "If Wayne is still here next Tuesday after the transfer window has closed I will not be unhappy.
"I want what is best for him and that is to play football week in, week out. Wayne is the cream of our academy and he will develop into a proper player. I thought he handled a difficult situation very well when we played Spurs at the weekend."
Goalkeeper Gabor Kiraly was also impressive in the 3-0 win and Dowie confirmed Palace have opened talks with him about a new contract.
The Hungary international signed a two-year deal when he joined as a free agent in the summer but has made enough appearances to trigger new negotiations.
The manager said: "Discussions are on-going with Gabor. We had an agreement to review his contract and he has done really well for us. We are hoping to sign him on a longer deal."