My guess is they'll release a few examples/betas of the character creators every time they're finished (er, almost finished?) with a new species.
I think I'm going to stick with FH for a while after Aro'Kai comes out. I do really enjoy FH, especially for the cute stylized look of the characters. Aro'Kai is amazing for more realistic species. I'm really interested in their gryphon species and I'll probably start really getting into that when they release the gryphons-- And even then, I'll still play both games. Both of their concepts are equally appealing to me, but for different reasons, because both games focus on different aspects. Each one has features that aren't available to the other, and especially with Aro'Kai not even released yet I'm hardly going to go freaking out over which one is superior.
As for if FH will die? Probably not. If anything, the people who hang out in FH playing horses/phoenixes/owls/whatever will all move over to Aro'Kai when the owls and ungulates are released, and things like that.
Both will still have ridiculously high populations of Simbas/Scars/Kopas/Kovus, though.
*shot*
