According to Claudio Colla of TransferMarketWeb.com, Ozil could be set to move on depending on the Gunners' success this season and Reus is the player on manager Arsene Wenger's wishlist who could replace him, as the Frenchman has not "given up dreaming" of recruiting Reus.
Per German outlet Bild (via Jack Rathborn of ESPN FC), Arsenal are attempting to tie Ozil down on a new deal, but if his contract demands aren't met, the playmaker could return to Real Madrid.
The German is an incredibly important player to Arsenal—arguably their best—but bringing in Reus to replace him would undoubtedly soften the blow should he leave.