When the original article came out I noted it didn't make sense for Apple to build a separate echo like device because users already have an echo, it's their apple watch on their wrists or phone in their pocket rather than buying an Apple Echo for each and every room of their house. And that AppleTV's already have a mic (the remote), and speakers (your tv or home theater speakers), which is why another product like the Echo wouldn't make much sense. They could add a speaker/mic to the appletv box itself but that seems little odd since the apple tv would have to be tremendously larger to have good enough speakers which seems like a waste since its already attached to external speakers. They could add a mic to the box but usually apple tvs are wall mounted behind a tv or in a electronic cabinet behind glass where they the mic wouldn't work.
So as noted before Apple already has an "Echo" with it's existing devices.