They have confirmed that the book will be available separately, though it's premiering in the gift pack.the whole selling it as part of a boxed set thing is crummy behaviour, and only forgiven because perhaps it's mostly a production issue.
The weird part there is that the carnival is a minor note in the book: the core of the book is 5 pretty seperate 32-page modules, and only the intro module is carnival related. The other 4 are very, very different.I'd buy a Feywild setting book but am unmoved by a big top/funfair (puke) themed adventure. Not much I dislike more aesthetically than that. Yeah I did NOT enjoy The Greatest Showman, thanks!
I fully expect to see all 3 in the next few years.If they manage to compound this by, say, a pure Spelljammer setting (yawn), and then failure to provide either a full Planescape (no Manual of the Planes nonsense will be acceptable if they go all in on SJ) or Dark Sun (either with a Psion or the setting reworked in a genuinely cool way that preserves the key themes) well, I may take a break until 5.5/6E, at least DMing-wise.