I'll admit I don't follow Euro basketball as closely as I have in the past, but I am not aware of Mirotic coming to the NBA. Last I heard he was making $5M or so in Spain, and Real was working on an extension. Can you point me to the source that says he is coming to the NBA next year?
I don't think anyone is saying he is definitely coming to the NBA, but this move looks like Chicago making it possible for him to come on over:
Luol Deng trade paves way for Nikola Mirotic to Chicago
http://www.sportingnews.com/nba/sto...s-trade-luol-deng-andrew-bynum-nikola-mirotic
The link discusses the possible extension with Real and how much the buyout would cost the Bulls and Mirotic himself.