I think the Nuva combine into the Kaita by creating the cube with the pieces. It would like the stones that became a sphere in the MNOLG.

That's a logical explanation, Extreme Kopaka, but only if the Kaita Nuva are implemented into the storyline. Otherwise it'll be like the Bohrok Kaita and Bohrok Va Kaita... No storyline importance whatsoever...
Here's hoping Lego proves me wrong!

In one of this site's interviews with Greg, he said they'd be in the comics. At least that's what I remember.

your good Golden Onua. You joined this month and you knew that. Yea Greg F sait that.