What does that even mean?
I believe they are saying that Sinnoh is to Unova, what Johto is to Kanto. I don't see that much of a connection though... especially since Unova is based on NYC America while Sinnoh is based on Hokkaido Japan, no real relation at all.
If they did do a Johto like region with a connection to Unova in Gen 6, then it would be something like England or Europe considering the historical connection to the early US states.
What are you serious?! For all my years of playing Pokemon I've never once made that connection.