I think a gradual shut down over a several month period while slowly taking away features to save money is a great approach. I do however think a pop up message inspiring people to be redirected to PeakD (Hive) would be a smart move right away and to keep up until the shutdown, since we are obviously all on the same page as to which is the more evolved (and more fair) platform.
Thank you for everything you guys do! I love the PEakD frontend, and have used Steempeak for a long time before the fork. Blessings.