Yes, they've said (or at least, heavily implied) that the next set will be DJ Pon3 and Octavia. Uh... Aren't
you [Brony Galore] the one they replied to with that little nugget of information in the first place? Anyways, I'm excited for both and we haven't even seen Pinkie and Lyra yet! I hope Octavia comes with her collar and bowtie. It'd just be weird if she didn't after Doctor Whooves got his tie.
For those that haven't heard, they've got larger scale ponies in the works, perhaps to be seen next year. They put "larger" in quotation marks, though, which has a couple different possible implications that I won't go into right now. It's been speculated that those will be the princesses (Yay!); although as popular as Discord seems to be among bronies, I wouldn't be surprised to see him get a figure too (I wouldn't care for it myself, but I'm sure it would be well received overall).
They have said that Trixie is on their list of possible future releases, but didn't have anything confirmed for her yet. I haven't heard anything about Bon Bon, but they'll probably get around to her eventually. I don't really care for her character or design, so she's another one I'd skip.
Personally, seeing as how they're already considering different body-typed ponies and how Hasbro really dropped the ball on Chrysalis (my opinion), I'd LOVE to see them do her properly. I know she has a more complicated design, but if anyone has a chance of getting it right, they do. In fact, releasing the whole villain line-up would be pretty epic, but I won't hold my breath on that front and will just be content with what Hasbro's given us so far.
Daring Do is another that I'd really like to see. I think I'd actually squee! And let's not forget Big Mac, Shining Armor, and the CMC... Really their list of possibilities is just endless.
Anyways, I think I need to steer myself back here. As for what I think WILL be released:
Pinkie Pie ---- Lyra Heartstrings
Octavia ------- Vinyl Scratch (loosely confirmed)
Twilight ------- Trixie (To me, those two just seem like they'd be a good pair to release at the same time, even if they're not the
next to be released.)
Applejack ----- ?
Rarity ---------- ? (I'm not sure why people think she'll be released with Vinyl; don't you think they have too similar an appearance?)
I don't know. Truth is, the only new characters we've really gotten from them so far is Doctor Whooves and soon-to-be Octavia. Everypony else has already been done by Hasbro. It makes me hesitate about thinking how far they're really willing to stretch. Are they going to play it safe or throw us some curve balls? I really don't know, and I find it exciting how unpredictable it is.
I'm fairly sure they'll release at least one more boy at some point, though. The poor Doctor is already pretty heavily outnumbered. Then again, given his track record of companions, he probably doesn't mind all that much.