Just like Paper FPs weren't going away ? Because they said nothing about that.
Just like pre-booking wouldn't be extended to offsite guests ? Because they said nothing about that.
Just like they wouldn't expand this to more than 3 FPs ? because they said nothing about that.
Just like everything else when people speculated about they were told, by the Pixie Dust Crew, "That will never happen, Disney wouldn't do that, they haven't said anything about that" etc etc.
It would be quite simple I'd imagine to "freeze" one bonus FP. Great way to spread the crowds out further, and maximize the capacity of under utilized rides at under utilized times.