Arsenal will be looking to strengthen in this transfer window, but they can only do that if some players are let go of.
Accountants advising The Arsenal Supporters Trust have forecast next summer’s transfer budget. A combination of a significant rise in the club’s wage bill and a drop in revenues after not qualifying for the Champions League is forecast to result in a sizeable operating loss. The projected budget takes into account the club’s significant wage bill, which was pushed to the limit in January when Mesut Ozil agreed new terms and Pierre-Emerick Aubameyang joined. The Telegraph report that the Arsenal Supporters Trust have forecast that the club will have a transfer budget of around £40million next summer.
So while many looks at the potential signings, it's important to analyse who can make room for the newbies.
Aaron Ramsey

It is obviously going to be hard for the Arsenal fans to see Aaron Ramsey to leave, but the reason Arsenal should look into selling him is by no means his ability. The reason is solely down to his contract position. It doesn't look likely that he will be signing a new deal, so in order to avoid losing him for free, it's important the Gunners listen to offers this January.
Danny Welbeck

Danny Welbeck was rumoured to be leaving the club in the summer, however, he managed to remain. He got a taste of life under Unai Emery. By Welbeck's standards, this start to the season is a very positive one. He has been on the scoresheet a couple of times from the bench, while also impressing whenever he has started in the Europa League and Carabao Cup. However, like Aaron Ramsey, Welbeck's current contract runs out in the summer. This is partly why Arsenal were open to offers in the last transfer window.
Carl Jenkinson

Jenkinson brings nothing to the table while reaping all the rewards of being a professional footballer. If Arsenal were a seriously run club, in the style of a super club, then the defender would have been out several years ago. He was expected to be a big thing when he was part of Arsenal's British core, but with the majority of those players moving on to better things, Jenkinson remained a bench warmer, and not even that at times.