I agree with some of your predictions.

- I think there's definitely going to be a Discord episode.
- Chrysalis and/or Sombra will return
- Rarity will get at least one own episode
- Derpy will reappear once again
- More exploring and intel on alicorns via the Twilicorn story arch
- Funny moments when Twi learns to fly with Dashie
- An episode focusing on the past of the alicorn Sisters
- Luna will get another episode or at least a bigger role in the entire Season
- More character development on Fluttershy
- Big Mac will get a talking role again
- I'd personally welcome more explanation on Cadence and Shining Armor, of course with giving bigger roles to them throughout the season.
- CMC: I think the CMC should get their marks at the end of the series, because this would mean an entirely new character arch for them and this would go beyond their purpose of existence, the CMC will come to an end if they earn their marks. However, the writers have proven us that they are not afraid to mess up the entire status quo of the show with alicorn Twilight, and she is the primary protagonist! If they took the high risks of making her a Princess, which pissed off a lot of fans, maybe they say: Buck it, let's have the CMC earn their cutie marks and create a whole new character arch for them! Oh, I'd love to see Sweetie Belle learn to use her magic though.

That's all I could think of right now.