His career was in mud when he was in last months in Arsenal. Then Barcelona came and helped to revive his career in Camp Nou. However, it did not last long because the transfer of Lewandowsky means the striker position is no longer reserved for Aubameyang.
He will have to compete with other attacking players to play at left or right swing. Forward position should belong to Ansu Fati. Things become bad again for Aubameyang. I am sure he will not be able to beat Lewandowsky and get the striker position in Barcelona squad.
Aubameyang and Lewandowski are short-term players for Barcelona, but there is good potential for Ansu Fati as a player who will become a long-term prospect for Barcelona. Auba and Lewa are two strikers who will educate Ansu Fati to compete to become a more mature player, so that is not the reason why he should fall.
Unfortunately Aubameyang doesn't seem to have much time to defend Barcelona considering he also needs enough playing time. Lewandowski's arrival has left him short of playing time, so he will have to try a move option and accept offers from other teams interested in him at the moment. Chelsea are ahead based on rumours, but I don't know which team will get him yet.