The layout as I understand it is as follows. Some of these have been completed and the plans could always change in the future.
Sterling (1) will host 1, 7, 16, 17
Chicago (C) will host C, 2, 5
Pontiac (6) will host 6, 8, 10, 21
Springfield (9) will host 9, 14, 20
Collinsville (11) will host 11, 18
DuQuoin (13) will host 12, 13, 19, 22
Oak Brook (15) will remain separate
I think the original plan had Collinsville and Pittsfield going to Springfield but there was a lot of angst about this in the Metro East area so these could stay at Collinsville for a while. Pittsfield had been dispatched by Springfield for a few years in the past.
Again, these are for dispatch operations only, the posts will likely remain for a while (at least). I could see closing some of them after dispatch consolidation is complete.