Is Adobe planning on sunsetting Scene7?
There is no such communication. Scene7 is rebranded to Dynamic Media. Please review the section "AEM/Scene7 integration versus Dynamic Media" of doc  to understand which option to go with.
Also, there is a session if you want to check: Scott's Digital Community: Ask the AEM Community Experts for June 2017
 Integrating with Dynamic Media Classic (Scene7)
There are no plans to sunset the Scene7 service, but it is no longer offered as a stand-alone solution.