Avengers: Infinity War was already chockfull of characters, but what we didn't know was that Guardians of the Galaxy regular Howard the Duck was supposed to make an appearance in the film.
According to the Russo Brothers (via Fandom):
I would have loved to see the Guardians actually interact with Howard at one point, but I guess with the way the movie was already tightly packed, they needed to get everything done without any unnecessary detours.
If anything, we might see Howard the Duck appear in the third Guardians movie should it ever push forward. Reports are suggesting that Disney is warming up to letting James Gunn back into the fold, then again, until there's an official announcement, we should all just consider it rumors.
Personally, a member of the Guardians who I want to see make it to the team is Cosmo the space dog. Cosmo appeared in the Collector's display in the first movie and made a cameo in the second film's credits. It's also worth noting that Cosmo appears in the Guardians of the Galaxy ride in Disneyland.
Will we see Howard the Duck again in the future? If we're lucky, he might even have a cameo in Avengers 4.
Avengers 4 comes out May 3, 2019.
See Also: Disney Reportedly Thinking Of Keeping James Gunn's GOTG 3 Script