Aubameyang is leaving the team for certain as far as I can see. And this is very likely to happen in January also. There are some big clubs in line to sign him already and Barcelona are one of them. Maybe Lacazette wouldn't leave in the same month but he is also likely to leave next summer I believe. Arsenal want to renovate their attacking line. And maybe En-Nesyri would be one of the proper choices.
I think that would be the wrong signing for Barca. Aubameyang is already 32 and Barca needs a new start with young hungry players in the current situation of the club. Also for financial reasons, this would probably not be a good option for Barca, since Aubameyang will certainly not take a big cut in salary and he was one of the top earners at Arsenal.
Why do you think it will be a bad signing for Barcelona? Aubamenyang is a good and prolific striker. He might be 32 but still firing. Maybe he is currently not on form and inconsistent in Arsenal due to few reasons, in or low level of commitment. He may have flopped in front of goal this season for Arsenal but desperate Barcelona fans want to believe that, with the service he would get playing for them, he would score plenty of goals. Aubameyang is good for Barcelona. l believe he can bring changes, Very smart and fantastic. And sometimes when building a new side involving young players, you need to add some bit of experienced players for them to learn from. It is part of the development process. Look at Arsenal, You have young players in Martinelli, Saka, Smith Rowe, Odegaard, White, Gabriel, Tierney and Lokonga. Playing alongside Thomas Partey, Lacazette, Aubamenyang, Xhaka makes them adapt and learn faster.