Who's seen this movie?
I finally got out to the big movie today.
The ending was pretty ... uh... as you say, seeing a show where the "bad guys" win... especially one where favorite characters die, can be a punch in the gut (...and yet we keep watching Game of Thrones...)
When it comes to bad-guys winning, I think Colonel Zemo "won" in Captain America: Civil War, as well... his plan worked to perfection, he got exactly what he wanted... but didn't lay waste to everyone in the way Thanos did. Seeing the Asguardians genocided and Loki's throat crushed in the opening scene kind of set a tone. Peter's reaction when he realizes he's dying gave me the feels.

Doctor Strange said he looked at a million possible futures, and only saw one where they beat Thanos. Later he tells Stark that giving Thanos the time stone was "the only way"... I assume he meant "the only way to get to the one future where we beat Thanos" rather than "the only way to save Stark's life".
This one set up the Captain Marvel movie in a year. That movie is set in the 90's, so obviously time travel will play into it.
I hadn't realized that Captain Marvel was to be set in the 1990s.
In the comic books, I believe that Marvel's original Captain Marvel (the male, alien one named "Mar-Vell") was constantly trying to foil Thanos' plans, so it would make sense that he would tie into this somehow. Reading through the cast of the Captain Marvel movie, I notice that they've cast Jude Law as Walter Lawson/Mar-Vell... so maybe that angle could fit into the resolution of this Thanos situation.
-k