As well as Kolasinac appears to be working out, I'd get busy in January signing 2018 Bosmans. These guys are pending to be available:
Leon Goretzka, CM, Schalke
Max Meyer, AM, Schalke
Jose Gimenez, CB, Atletico Madrid
Kepa Arrizabalaga, GK, Athletic Bilbao
And, of course, Messi could be available. (Hey, if you believe reports out of Spain, he sounded out Arsenal before signing his last contract.)