Not sure if they are announcing more or not, but it looks like Michigan is getting a really good competitor for Motor City. I think the state can support 2 major cons. There are a lot of really good medium to large shows like Great Lakes Comic Con, but there really isn't anything in the 20K+ attendance range outside of Motor City. Grand Rapids Comic Con doesn't have many books in the room, more of a cosplay/pop culture show. Also, I saw some booths there for things like gutter helmets....
Great Lakes was AWESOME this year with Jim Steranko in attendance and tons of comic dealers. That is the only other one I see with the growth potential in Michigan to challenge other bigger shows.