If Barca decides to cash in on Lewandowski, no club is going to pay a huge amount of money because of his age, except clubs from Saudi Arabia. Although, I don't think this is going to happen this summer because Barca appreciates his contribution to the team and wants to keep him. Since he moved to Barca, he has not decline in form. He has consistently being their top scorer, and this season, he scored 42 goals in all competitions. That's insane from a 37 years old.
So i don't understand if Barcelona wants to give away Robert Lewandowski or not. If they are rumors then they are doing it on purpose to fuel some kind of noise to make Lewandowski and Barcelona fight.
If there is nothing certain, then it means they are keeping it
It's hard to believe that Barcelona would part ways with Lewandowski at this moment. I think he's of crucial importance and can still play at a top level for at least two more years. With these young players around him, it will be even easier for him and he'll be able to score more goals. But again, at the end of the day, these are just rumors.