So I've had this idea kicking around in my head, and I haven't seen anything in the forums around here that suggested the same(either that or my searching ability is lacking). So here it is:
Could Cultivation be the 'red mist' that Sazed shows to Wax and the one infiltrating Scadrial under the guise of Trell? For the basis of this I am assuming that Odium is defeated and Rayse killed at the conclusion of Stormlight 5. Rather then Dalinar uniting Honor and Odium, Cultivation picks up the shard to create an intent that is hatefully destructive in its quest to grow things.
Scadrial is seemingly frozen - I believe Harmony mentions how little progress has been made because he made the Elendel Basin too perfect. The planet is not being 'cultivated'. Cultivation in combination with the Odium Shard would be compelled by intent to change this. Destroy what is currently there, then cultivate it as she sees fit without the influence of Harmony.
Cultivation has been playing the long game to take out Odium/Rayse. Perhaps the death of Tanavast caused Cultivation's vessel to stray off the path of benevolence and she decides to remake the Cosmere as she sees fit.
This is highly unlikely, and I'm sure it has a ton of holes or even a WoB that completely debunks it, but Autonomy or Odium just seem too obvious a choice to be Trell/Big Bad. A Cultivation/Odium pairing would be interesting to say the least.
Thanks for reading!