Does Ep.9 need to end on a 'happy' note?

I'm not sure if I could be convinced that anything is "the end" short of the destruction of the dark side itself after ROTJ was supposedly the end.

 

I think that you can have a darker depressing ending for your trilogy. But there is a condition. There needs to be a resolution and most of the questions need to be answered. example at the end Rey can turn to the dark side and that can be the new conflict for a future story but the conflict between the resistance and the First Order must come to a close in some fashion, Also I don't think it can be totally horrible. My example of a good dark ending.

Snoke has been slane and Rey takes command of the First Order.

Poe and Finn are the only survivors of the resistance.

Kylo Ren is betrayed by Snoke and ends up with Poe and Finn.

Realizing that Rey must be stopped, Ben Finn and Poe join forces and go into hiding to begin there new rebellion.

There is resolution in that the main conflict has a declared victor, but its not what you really want to happen. just like RotS. The Republic beats the Sepratist army and the clone war is over. but the sith have taken over the government and turned it into an empire. but just like you have your next generation change things the other way so would be the case in a potential X XI and XII. taking place 20 some years in the future and using Ben's son or daughter as a rookie pilot in the new rebellion under the command of Poe, and Finn. Meanwhile Ben is trying to train Jedi to build up forces to use against Rey. perhaps Ben has already trrained his son/daughter by the beginning of the film or or perhaps his kid is still in training with Ben.

With all that being said, unless a film ends with the bad guys losing it won't feel like its truly over. even Hunger Games which had its bad guys lose was able to give a depressing ending that left you noxious. I think that was the beauty of RotS The Good guys won but so did the bad guys in a certain sense. and that would be the interesting thing about my ending is that even though the resistance falls The "good guy" Rey would have the ultimate victory. but not a good victory.