I don't think Wenger would be upset if he signed Lemar and also had to keep Alexis and Ozil. One good striker, two good wingers and a good number 10, it sounds like the team we've been moaning that we want for years now.
Young winger maybe capable of turning his hand to central midfield? My first instinct is Chamberlain replacement.
He could replace Perez too in the squad and spending 100m on 3 players sounds like a standard modern Arsenal transfer window, except we'd likely recoup 30-40m on Chamberlain / Perez too.