Ok so I'll be listing my current deltarune beliefs and speculations in this post just so I can come back whenever ch5 releases and see how much I got right or wrong
There's no way Dess is the Knight. My bet is on either Rudy or Carol, if not both (given the difference in mannerisms between Chapters 3 and 4)
Weird Route ends in Ch. 5, and at some point we lose control of Kris in exchange for Noelle becoming our new vessel.
Asriel is not dead. Why is this a theory to begin with
Chapter 5 Dark World will either be inside Flower King or during the Festival
I'm more leaning towards the festival on this one, maybe Asgore opens it up in a public space in an attempt to show people "what really happened", whatever that is (supposedly related to the dess case)
Asgore bossfight (Either as main boss or shadow crystal boss) regardless of whether or not the DW is in Flower King or outside during the festival
More focus on Ralsei's character arc
Rudy fucking dies during the festival
This isn't as much a theory as it is something I think would be super cool, but I really want the festival dark world boss to be a giant ferris wheel monster
The final prophecy pannel that susie shattered either claimed someone must be sacrificed (my bet is on either susie, noelle or ralsei) or the Grand Fountain being sealed away.
NOTE: Sealed not as in ceasing to exist, since that would just fuck up the balance between light and dark again. I mean severing the bond between the light and dark worlds and having them exist in isolation
The Vessel won't be playable
The Angel will either be Dess or the Player