I actually don't see Thor appearing in the next Guardians movie as James Gunn wrote that script ages ago, but I can see some of the Guardians having a part in the next Thor movie. Rocket and Groot, in particular I can see.
I really would like to see some follow-up on Queen Brunnhilde and New Asgard (I'm reasonably sure she has been given that name in supplemental materials, if not on screen).
Also, something I just thought of. It was stated before Stormbreaker was even forged that it could summon the bifrost. In fact, that was the first thing Thor did with the thing. So, then why does he need to ride anywhere with the Guardians?