That doesn't necessarily mean they're gone after the 2014 season, but Tribune has 30 days to meet the higher assessed market value of the broadcast rights. After that, the Cubs are free to negotiate with another station or form their own network. If the Cubs hadn't done this, they'd be locked in through 2022.
This doesn't affect games that air on Comcast Sports Net, nor does it affect their games on WGN radio (IIRC, they just reupped with them). This is just for the 70 games that air on WGN-TV, WGN America, and WCIU-TV.
http://www.bleedcubbieblue.com/2013/11/6/5073176/cubs-opt-out-wgn-tv-contract
This doesn't affect games that air on Comcast Sports Net, nor does it affect their games on WGN radio (IIRC, they just reupped with them). This is just for the 70 games that air on WGN-TV, WGN America, and WCIU-TV.
http://www.bleedcubbieblue.com/2013/11/6/5073176/cubs-opt-out-wgn-tv-contract