I'd prefer to keep Rodri even if it meant losing him on a free next year. But if they were to offer silly money (which I doubt), I'd expect the club would take it.
If that happened, I'd be going all out for Bruno Guimaraes. Losing Rodri and Bernardo at the same time would leave us in desperate need of a world class controller in the midfield. Nico G, Anderson, Wharton etc have potential to be that player. Bruno G is that player already, and he has 2 years left on his contract at Newcastle. It would take a huge offer but we'd have the money.
As I said though. I don't expect Real to go high enough to make a deal this summer worth our while, unless Rodri forced it. And I don't see any reason why he would.