A while back Rory said the app would be free and for a modest cost, users could get additional features. That was maybe back in the Summer and of course things could have changed since then especially when Facebook see the app and now it's closer to reality.
I think in the update last month, Rory said they had to go through approvals, etc. He didn't mention that in the LD Micro video this week and he said they were going to finish it this month and launch in Jan. Sounds like it has been approved or they don't think that will be an issue.
I am going to take a guess here and say nFusz has a stand alone app that pulls in FaceBook live so you can add interactivity. I don't see how it would be "built in" to Facebook life out of the gate. That's what it sounded like and if that is the case, the freemium model would work nicely. Remember, this will tie into the Brightools/nFusz app as well.