According to Nick Confalone, it appears that Sunset's Backstage Pass is going to be our last of the Equestria Girls specials unfortunately, coming as a surprise even for the team behind the specials. Looks like as pony starts to wrap up that we are seeing parts of Equestria Girls wrap up as well.
You can find the whole thread at the link below. Thanks to Maik for sending it in!
Source
Twitter: Calpain