Twice William Link & Peter Falk have sought out other interested networks for broadcasting new Columbos. Several years ago, A&E announced plans to back future Columbos, but instead ABC flexed its contractual muscle to put out "Columbo Likes the Night Life", which pushed for a drastic change in the format of the mystery series sans any advertising budget.
Last year Universal Studios was bought out by the company owning NBC. It was reported Link & Falk courted the new NBC management for new Columbos, but ABC appears to have flexed its contractual muscle once again.
If you recall the various season announcements by ABC many years ago, it had announced the backing of three more Columbos. The first of those three was much delayed release of Columbo: Murder With Too Many Notes. If my calculations are correct ABC can only pull this stunt one last time.
We can only hope for Falk sake that there's a Sean Connery Clause in the contract that states ABC "Pay or Play".