I'm confused ... Bakker is writing a book The Crabikiad? Will this be part of the next books proper or a side story?
Lol, no. Bakker said here and at Zaudunyanicon that he envisions TNG as a kind of new Sagas. He's also said across those interviews and at the AMA that he's focusing on the Boy's story next (which is part of the main story), which will probably be its own book and will likely stand-alone in terms of the rest of the follow-up he's leaked so far. He said at Zaudunyanicon straight up that if he wrote it after the other two or more books of TNG that people would think it a cheap add-on so he wants to do it first.
Wilshire dubbed the Boy Crabicus and pail following along the new Sagas sentiment called Crabicus' story, The Crabikiad.
Also, noted, that Bakker didn't seem to like at all that those two fan-namings had occurred, which garnered much laughter at Zaudunyanicon.