I hear that parts of Season 7 and those Equestria Girls specials will be unveiled at Natpe Miami in a couple more days. And later all this year, we'll get a total of 29 installments within both franchises on Discovery Family.
Now, the writers -- some from Season 6 are returning, while others are likely to get replaced.
Josh Haber - It's currently not guaranteed he'll return, but in the past two seasons, he didn't put much of Pinkie, Applejack or Fluttershy in his episodes. Maybe that "Daring Done" episode will come from him.
Michael P. and Wil Fox - These boys wrote TWO RariJack episodes in Season 6, plus another Rarity one with "Forever Filly". But then comes an episode where, for the first time EVER, Pinkie Pie and Fluttershy are the only two Mane Six ponies to appear in it! Seems like the Foxes are starting to neglect Rarity by now.
Joanna Lewis and Kristine Songco - In the last two seasons, these writers mostly put Rarity and Rainbow Dash in their stories, except in one (The Hooffields and McColts). But trust me, I don't think Lewis and Songco are RariJack fans because Applejack didn't appear in almost every one of their episodes until Season 7, and Rarity only got one major role out of them (plus, she didn't even speak in the first episode of this season). I'd say they're more like Starlight fans.
Dave Rapp - Not yet confirmed, but he's the one who introduced Fluttershy's family.
If he gets confirmed, he could be the writer of a possible episode focusing on both Pinkie and Fluttershy's families, but chances are, it may not be very likely. UPDATE: Since Maud Pie was confirmed in Pinkie Pie's next episode where she doesn't share a major role with any Mane Six pony, there probably won't be an episode focusing on both Pinkie and Fluttershy's families at all. So I'm now not really sure what episodes Rapp will have for us.
Ed Valentine - Did no work whatsoever in Season 5, but wrote two episodes focusing on the Cutie Mark Crusaders in Season 6. There's a possible chance he could be the writer of Campfire Tales and/or Marks and Recreation as well.
New writers so far who we could see next season:
Sammie Crowley & Whitney Wetta (A Flurry of Emotions) - They wrote a Twilight episode with Pinkie in it. But they might give us an Applejack or Rainbow Dash episode after that.
Nick Confalone - Another writer had returned for Season 7. Two years ago, during Season 5, he wrote two episodes focusing on Pinkie Pie, but at that time, he was a new writer, and now, we get another Pinkie Pie solo episode from him, again! P.S. It's his only episode this season.
G.M. Berrow - The writer of Fluttershy's first Season 7 episode previously wrote a Pinkie Pie episode. But unfortunately, she's also the writer of one of the three Equestria Girls episodes, so I guess that's all we're getting from her this year outside of books.
Josh Hamilton (Parental Glideance) - He's the one who introduced Rainbow Dash's parents.
Kevin Lappin (Honest Apple) - Next time he writes an episode, it most definitely can't be RariJack.
May Chan (Not Asking for Trouble) - If another episode comes from this writer, it probably won't be a Pinkie Pie episode.
Writers who shouldn't return next season:
F.M. De Marco - For that 28 Pranks Later episode.
Becky Wangberg - For that Hard to Say Anything episode.