Seeing his contract out here makes it unrealistic to go back to Benfica sooner. Going to Saudi Arabia to make many years worth of wages in two or three would make a return to Benfica plausible. Not that I believe he actually wants to return to Benfica
Doubt the Saudis would pay an 80m fee and more than 25m a year, to have him for only 2 seasons. Which is what he has left with us. IF, Benfica is the route he wants to go down, which in fairness he has consistently said. But I think he would want another European club in the meantine, probably Barcelona. If it doesn't come, to me it looks like staying is his better option.