I don't know if you've heard this rumor that has been going around about the Silver Surfer possibly making a cameo in Avengers: Infinity War, but I think any fan with common sense would realize there's no way that would happen. Sure, it would have been freakin' cool, but as of right now, Marvel Studio still doesn't own the rights to the character.
Directors Joe and Anthony Russo recently did an interview with Yahoo Movies, and during the interview, this rumor was brought up with them. When asked about it, Joe Russo says:
"I don’t think we own Silver Surfer. But it’s fan-wish fulfillment and, you know, if this Disney-Fox deal goes through there’s going to be a lot more characters coming into the Marvel universe, so some of those crazy fan theories might come true."
It's just not going to come true in Avengers: Infinity War. That doesn't mean we won't see any other surprising unexpected characters in the movie! Who knows what's going to happen or who's going to pop in! After all, there are over 60 characters in the movie! Anthony Russo goes on to talk about the process of putting the movie together:
"It’s hard to second guess, you know, part of the beauty of these movies is that there are so many different directions that you can go. There are so many different choices you can make and I think that’s part of the fun of the process for Joe and I, in those early days, feeling out where we want to go with the movie, sitting with Marcus and McFeely and the writers, talking through all the possibilities, and once you centre on a road, just running with it. I don’t think we have any regrets about the choices we’ve made I think we’re very happy with it, but yeah, the material is infinitely malleable."
I think the fans are happy with what they've given us so far as well. We don't really know how exactly the story for Infinity War is going to play out, but I know that we all expect that it's going to be amazing.
As for Silver Surfer not being in the film, that's fine! I'm sure that one day he'll get an epic film of his own when the rights do eventually end up back at Marvel!