I haven't seen this anywhere except Scott Fybush's Twitter feed and FCC-CDBS but...

WBBM-780 Chicago has filed to relocate their transmitter. They plan to share the tower of co-owned WSCR-670 a few miles to the southwest. To avoid interference with other stations they will need to reduce power slightly. (and because the WSCR tower is "too tall" for 780 and will be more efficient) WBBM will remain a non-directional Class A clear channel.

The area around the existing WBBM antenna is full of office parks and shopping centers. The land is extremely valuable.

WGN-720 is nearby. This station was recently sold. One wonders if they may also be considering a move?