Surely we get another Thor after this.
The box office for this movie might not be the only factor there. Having done a trilogy for the big three "phase one" characters, I think the studio may want some other characters to come to the forefront after Avengers 4.
A Spidey trilogy, Black Panther, Captain Marvel. Another Doctor Strange movie.
The Asgardians and Thor are now in a position where they can move into the background for a while, or appear in a supporting role, when appropriate.
We might see a character like Valkyrie get some more development in phase 3. I think there's definitely great potential there. She was one of the best parts of this movie.

. The thing to remember about the Marvel Comic book universe is that it has always been cross pollinated. Heroes from other books come into the books all the time. There's no reason for Marvel not to follow that pattern and have other super heroes in a movie centered around another super hero.It worked with Homecoming and Ragnorak.