We do know that the MCU version of Nebula hates Thanos as much as anybody, so it’s a safe bet that even if Nebula isn’t a hero, she’ll be on their side when things get serious in Avengers: Infinity War.
We know that Nebula will be an unenthusiastic member of the team in the new movie.
It’s possible that we’ll get some hint of what’s next for Nebula when we see Guardians of the Galaxy Vol. 2 next week.
Whether she’ll remain one of the “good guys” at the end or end up someplace else entirely may give us an indication of where things are going.