So you know how Gen 2 remakes still had Kanto? Well I think that Gen 5 sequels were supposed to have Sinnoh, along with all the juicy content it already gave us.

>Cave of Being
Deepest part is said to have led to the Sinnoh region
>Gardenia Flower girl
A girl in a Pokemon Center mentions the story of Gardenia Flowers of Sinnoh.
>Cresselia and the Ghost Girl
Cresselia can be battled on Marvelous Bridge, and the Ghost Girl in the abandoned Lentimas House was in a nightmare brought by Darkrai
>Flocessy Ranch
The Hiker theme of Sinnoh is remixed into the Flocessy Ranch theme
>Iris
Iris tells Drayden of a Sinnoh myth in Drayden's flashback
>Skyla
Skyla mentions Sinnoh being some ways away, but not around the corner

Sinnoh was probably supposed to be in Black 2 and White 2, but was cut out in the end cause of how big the sequels were already. Will Unova appear in Gen 8 with Sinnoh? Gen 10? What are your thoughts on this?