To be honest, what would be great for the sequel would be to show how they've all moved on in their lives - where they are now, etc. Kinda like the ending to Digimon 02 I guess. Genta runs an international chain of sushi restaurants, Mako is now a cat lady, Ryu has become a hermit living alone with a statue of Takeru which he talks to ala Helga in Hey Arnold, Kotoha becomes a street walker, Chiaki is in jail, and Takeru and Kaoru struggle with the nature of their relationship....
Oh, and Jii and Tanba become SHINKENWHITE AND SHINKENBLACK GUYS ITS GONNA HAPPEN THEYRE GONNA SURPRISE US
Also - THE RETURN OF SHINKENBROWN!
And for the sake of the active board 'feminist' I'm sure we can all expect a healthy dosage of all the big bad boys in the sequel slapping the women and putting them in their place.
Because, y'know, that's what Shinkenger is REALLY about.