Hasbro said they're committed to Equestria Girls until 2017 like My Little Pony. Of course, this will depend on toy sales.
For closure, I'd want to see the Equestria Girls cross into the portal to Meet with the Mane 6 in Equestria.and vice versa. Seeing Rainbow, Pinkie, Fluttershy, Rarity, Applejack cope with hooves/hands on either side would be hilarious like Twilight.