Silva left for Sociedad in La Liga, but yeah, Messi would slot in on the right wing with Jesus or Aguero up top and Sterling on the left. Throw in Debruyne with his precision passing, and that's a heck of an attack.
Thinking about it though, they'd probably have to unload somebody, b/c they also have Bernardo Silva and Mehrez that usually play right wing. Unless you put Messi at the 10 and let Debruyne play the 8. Financial fair play comes into effect too.