Theories POSSIBLE SPOILERS
Mr. Fetlock will become Pharoh Phetlock.
- He is a beluguered stallion who is very stressed and angry over the actions of the Power Ponies and on his museum. His very name also lends to the possibility.
We will see other characters with Jumpsuits
Given how prevalent the jumpsuit fad is, we might see other ponies/beings wearing jumpsuits.
Dealancy designs Flutteshy a jumpusuit as a gift.
Delancy, going with the times, might decide to design a jumpsuit for Fluttershy as a way of making it better than the other jumpsuits. It might even be a good look for his Queen of Chaos to be.
Fluttershy will end up revealing her identity to Delancey.
Saddle Rager will protect Delancey in some fight and end up revealing she knows him, or Fluttershy will do something to protect him (like deflect magic) that will force her to tell him her identity.She may or may not reveal her connection/attraction to Discord. Delancey may start to feel guilty about hiding his identity from her.