That was said by Enrico Galliera: https://edge.media-server.com/m6/p/ietfjftk His reply starts at 2:05:15 ("..higher performance versus LaFerrari"). I don't think the BB will touch it, the Valkyrie is a really extreme machine.
So that is my point. Until 2023, Ferrari has nothing to fight it with. And there is a demand for the typical 10 year supercar and another one that sits atop of it. Even if it's a one time thing as market is good and full of new billionaires. They are missing out and clients are left without a Ferrari in that price range.
It won 't be wise to turn the once-in-a-decade hypercar into a regular theme. There are two reasons for this: a) There has to be a meaningful technical and performance leap between generations and b) they have to remain rare and special.
ferrari tend to keep their projects secret. Most of us do not know what will come from maranello in next few years. 3 years ago the valk project was publicly unveiled but still no real running prototype. On the contrary the BB is in its final development stage and we were only informed about it few months ago. The bb's 0-60 mph is 1.9s against valk's 2.5s. And what about the upcoming (discussed here in fchat) v12 icona/new f40/testarossa or whatever with 1000 hp and 0-60mph in 1.9s?!
Aren't those the rumoured specs of the BB too? Anyway, I agree with your overall thoughts (And Zeus' above). Ferrari keep most of their projects really secret and they don't need to hype anything up. When right moment arrives, we will see the next hypercar worth of a halo status.