Lewandowski will be let go by Barcelona I think. That's also because there are rumors that Lewandowski is asking for a salary increase. which I think must be adjusted to improve performance.
If Xavi finds another alternative in the transfer market, Barca may release Lewandowski.
If indeed Lewandowski asks for a salary increase, it seems I agree with you that he will be sold to another club to make a profit rather than increasing his salary but it won't have a big impact on Barcelona.
I have previously heard that Lewandowski actually wanted to be sold by Barcelona but he refused when there was a big offer from a Saudi Arabian club so maybe Lewandowski received a bigger offer from a European club.
The question is quite difficult, which European club is willing to buy old players at high prices? It's a little impossible but it could happen unless he gives a very strong performance this season and releases him in the next transfer market to give confidence to other clubs to offer him a big salary even though he looks old.
But it quite difficult for Lewandowski to improve his performance because his old age prevents him from increasing his performance level because his physique is definitely very different.