Although Lewandowski has reached an agreement with Barcelona to stay with Barcelona until the end of the season or one more season. But Barcelona must move quickly to find a replacement, Barcelona is currently eyeing Newcastle United striker, Alexander Isak, and Viktor Gyokeres from Sporting CP is a more affordable option with a cheaper transfer value.
Barcelona management will not take the risk too quickly to find a replacement for Lewandowski in a financial condition like this. As long as Lewandowski can still be relied on, Barcelona management will look for a replacement player with an easier option such as a player who has free agent status. And in my opinion if Barcelona is eyeing Alexander Isak, it is just a rumor. On the one hand, Newcastle will not release the player at a cheap price and while Newcastle currently still needs the player. So at this time Barcelona can only survive with the existing players and look for a replacement player slowly without rushing which can put more pressure on Barcelona's finances.
In fact, Barcelona managed to bring in young star players from the youth academy during this period when they were experiencing financial difficulties. Lamine Yamal in particular continues to leave his mark on world football. If they can produce a striker from a young youth academy like Lewandowski, I think Barcelona can maintain this squad for a long time. Most of the players are young and due to financial difficulties they have to turn to free agents. They also have to keep experienced players like Lewandowski.