Here's a list of stuff I want the show (and EG) to address before it ends. Give me a heads up if there's something I left off this list. I tried to be pretty thorough.
Antagonists (reformed or not):
- Discord - Where did Discord come from? Why was Discord not around during the time of the original Hearth's Warming, and what caused him to rise to power? Are there other Draconequi? If not, why does he have a species name?
- Sombra - Who was he? A former student of Starswirl gone bad, perhaps? Did he die, or will he return eventually?
- Chrysalis and the Changelings - How did Chrysalis become the Queen? What's her baggage? How did the Changelings all become "unreformed" and gain their classic, black, withered appearance? Were they always like that, or not? What will Chrysalis's revenge plan be? Will she be reformed? Were all of the Changelings reformed, or just some?
- Diamond Dogs - It just feels weird to have them lying around doing nothing, will they ever make a return?
- Scorpan and Tirek - We need to see Scorpan!!!
- Diamond Tiara - We need more post-redemption content for her and Silver Spoon. On a related note, we need an episode that focuses a bit more on Tiara's mother. She can't just be generically mean/snobby, she has to have some sort of backstory as to why she acts this way. Her upbringing? Something else?
- Dr Caballeron - Why did he go from wanting to be Daring Do's partner to a crimelord?
- Lightning Dust and Wind Rider - Will they ever get a follow-up episode?
- Most of the one-off antagonists - Are we ever going to revisit one-time characters like Suri, Zesty, etc?
- The Tree of Harmony - Where did it come from? What's the story behind it?
- Mage Meadowbrook's Eight Enchanted Items - Will they make an appearance, now that Meadowbrook will be (sort of) appearing in Season 7B?
- Crystal Heart - Where did it come from? Does it have any relation to the Fire of Friendship?
- Fire of Friendship - Where did it go? Does it have any relation to the Crystal Heart?
- Alicorn Amulet - Where did it come from? Where did Zecora put it? Will it return?
- The Royal Sisters - How did they get their cutie marks and ascend to alicornhood? How did they know Starswirl? (NOTE: I no longer consider the Journal of the Two Sisters to be canon, thus why I put this here.) Will Daybreaker ever be brought up again?
- Pony of Shadows - Was it Tirek, hiding at the castle after his escape? Was it Zecora? Was it something else entirely?
- Prince and Princess from Hearts & Hooves Day - Who were the Prince and Princess? Was the "chaos reigning" that was mentioned how Discord took over Equestria?
- Bright Mac & Pear Butter - What happened to them? How did they die? [Unlikely to ever be answered.]
- Daring Do - Why was she so against having partners? What's her baggage?
- Star Swirl the Bearded - What was he trying to do with his masterpiece? Did he die, disappear, etc? What is his relation to the Royal Sisters? Does he have descendants?
- Muffins - We keep getting all of this background backstory stuff for her lately, and I can't help but wonder if they're building up to something. Perhaps we'll get her backstory in Episode 200 / Slice of Life 2 / S9E5 if we ever get that far?
- Mirror Pool Pinkie - Will she return for an episode in the future, or remain a background gag?
- Pinkie Pie - Why does Pinkie's whole family have strange powers (Pinkie Sense, Maud Sense, Pinkie's reality-breaking powers), yet the Apple family doesn't, despite the supposed relationship?
- Flutterbat - Will Fluttershy's fang at the end of Bats! be mentioned again? Will Flutterbat make a return?
- Spike - Spike's relation with Rarity seriously needs a conclusion, and I'm sure we all know the conclusion is a hard "you're cute but no" from Rarity. Also, how did Celestia's school get Spike's egg? Who are his parents?
- Babs & Manehattan CMCs - We keep hearing about the Manehattan CMC, but at this point they might as well be nonexistent. Perhaps an episode that focuses on them? Also, Babs needs to make a reappearance.
- Scootaloo - Scootaloo can't fly, and Spike will never grow wings (if his adult form from Season 2 is any indication)... this needs to be the focus of an episode. Also, is Scootaloo an orphan, or does she just have parents who don't pay her any attention?
- Rainbow Dash - Several people (myself included) think that Dash is destined to become either a leader or the leader of the Wonderbolts by the end of the show.
- Griffonstone - How is it doing now? Has it improved at all since Dash and Pinkie went there?
- Unvisited Locations - The Zebra Lands, Arimasti Territory, Hollow Shades, etc. We need to see more of Equestria, you stupid Cutie Map!!! Send them somewhere new!
- Will the Sirens make a return now that magic is leaking from Equestria?
- The magic leaking from Equestria is building up to something big... Magic Apocalypse, perhaps?