Plus they have to pay for other players, whether in installments or otherwise. Some people are acting like this year's payment to Napoli is all that they have to pay out.
Besides, the only thing that anyone has to go on about whether or not Juve can pay for Higuain and keep Pogba, is coming from Juve themselves. Which is exactly what you would expect them to sell. If I buy a new house down the road before I sell my old house, I'm not going to tell potential buyers of the old house that I need to hurry up and sell. I'm going to say that I'm thinking about keeping the old house, it has a lot of sentimental memories, maybe I'll put my in-laws there so that they're closer to their grand kids, etc. I sure as hell aren't telling them that I'm going to go bankrupt if I don't sell the house ASAP.