Season 6 General Speculation v10

I think Ellaria dies immediately after she's arrested.

There's no way Doran would even know about Myrcella's death until someone tells him. I picture it this way:
6x02- Jaime returns to King's Landing with dead Myrcella and Trystane, Kevan writes a raven to Doran questioning him on the attack and sends a small force of men to the Water Gardens. Cersei keeps Trystane under like
house arrest.
6x03- Doran gets the message and immediately has Ellaria and the Sand Snakes arrested
6x05- Ellaria Sand confesses to killing Myrcella, and agrees to be executed as long as Doran spares Oberyn's daughters. He agrees. Kevan's force arrives and watches as Areo Hotah beheads Ellaria Sand.
6x06- Doran releases the Sand Snakes, on the condition that they work for him. He tells them his plans and gives a version of fire and blood. Cersei has Trystane killed.
6x07- Doran and the Sand Snakes meet with Varys and discuss an alliance with Dany.

Ravens exist. Jaime arrives in KL in the premiere, Doran could easily be informed in time for 6x02. Also you seem to forget Arya magically knowing that Tywin died in 5x02.

That + I don't want Doran to be a coward pussy. He's a great character, if he has no plans nor a spine, whole Dorne is just a shitpile apart from Oberyn. He said he doesn't believe in third chances. Ellaria could've gotten Trystane killed.

I think it will come down to Doran and Kevan communicating. I imagine the Crown will want her dead in exchange for a guarantee of Trystane's safety. Which I think would need at least an episode to set up the logistics of. Unless my Varys theory is correct, I'd see her then being in two episodes as the politicking behind this agreement is set up. This would stabilize KL-Dorne relations more or less until Kevan and Pycelle are killed and Trystane is then in Cersei's custody not theirs and until Dany leaves for Westeros. That will throw the relationship back into chaos. And then war.

EDIT: Which would be my response to your above reply as well, @alcasinoroyale

Also whatever else she schemes in the meantime, it will be Kevan and Pycelle making the decision-making at the beginning of s6. s7 is when I imagine when she kills Trystane after she's won her trial and again has the regency in her control.

So that probably means it will take Mel multiple attempts to resurrect Jon. 

I mean what else would happen, they burn his body, Wun Wun and the wildlings break through the gates, and Jon rises from the dead.

I think Mel is going to bang Jon's corpse back to life but will need 3-4 different attempts (different positions each time). She probably gets really tired afterwards and accidentally falls off the top of the Wall to her death. Hell of an arc for Carice though, she's probably already getting butterflies waiting for the inevitable Emmy noms.