That may work for an unannounced test, but it would cause chaos if done that way on a regular basis. It wouldnt take long for people to find out that the first few hundred people to get to a line can get in and everyone else is shut out entirely. What they do now would make a lot more sense. Several thousand guests get reservations, and some smaller percentage can experience the attraction as long as they are willing to wait. And keeping the posted wait time longer than the actually expected wait time will ensure that there aren't too many people in that line.
So, I say the same thing I said last year. I don't think any of the new rides will be totally FP only. They may be de facto FP only for people who are unwilling to wait in a 60-90 minute line or participate in a rope drop dash. And, the more popular they are, the more difficult it will be to get FPs.
As for the small pavilion, we don't know what the area will be like when all construction is complete. The entrance to the ride may come from behind or to the side of the building and not from the front where the Maelstrom entrance was. And there may be a lot more queue space inside the building than there was for Maelstrom.