Precedent that must be applied or followed is known as binding precedent (alternately mandatory precedent, mandatory or binding authority, etc.). Under the doctrine of stare decisis, a lower court must honor findings of law made by a higher court that is within the appeals path of cases the court hears.
Update at 9:55 a.m. ET. 'Talk' To Go Off The Air At The End Of July; Decision Came After Discussions With Stations: The New York Times adds that the plan is the product of discussions that began more than two years ago between NPR and some of its biggest member stations.
Honestly, there was no talk pre- the finale of the show; we only found out a week and a half ago that it was going off the air and ABC [executives] were watching the pilots [in contention for a 2015-16 season pickup]. But fans love the idea, and I've heard that Gabriel is embracing the idea.