And you know this how? The players in their prime aren't going to fall of a cliff and they have players like Casemiro, Carvajal and Varane, who aren't old at all. A better goalkeeper like Alisson and new striker like Icardi could be more than enough. And buying for the sake of buying isn't going to help them catch Barcelona. They've been a lot smarter with their signings recently, e.g. Kovacic, Ceballos, Asensio, Theo Hernandez, Vallejo and promoting Hakimi from within. Zidane might have given them the necessary change the squad neeeds along with just a couple of signings.