Honestly, i think that the only important player that will leave will be Luisão.
Luís Filipe Vieira is constantly talking about how Benfica needs to create a structure of players that identify themselves with the club. He's also saying that Benfica will keep the best players if the fans show that the club can count on them.
We are about to become portuguese champions after 11 years. The merchandising of the club will suffer a tremendous boost in sales, we'll get 5m € from UEFA just for playing there, and we'll have to add the money from TV and the packed Estádio da Luz during the competition.
As shown by the recent study, we are 14 millions. We have to find a way to bring those 14 millions closer to Benfica, and Benfica TV will be a money making machine (even without the football games).
My point is, Benfica is in a difficult situation, no doubt about that. But in the near future, we have what it takes to succeed without selling players every year.