if you mean "good busines" in tearms of money then yes, its a good business selling him now and get more money.
if you mean "good business" in tearms of the team, then no, becouse you will have to bring a new player who will need time to adapt to the team and the league, lest take the example of Torres, he is great, but how can we know if he will still be great playing in Italy? nobody and in the best case, he can adapt the Italian Legue, in the mean time who will be our finisher? , thats why the best thing would be, buy a young player, giving him one year for him to stablish in the team, and when we know that the player can full Trez shoes then sell Trez.