Ralph was first playable in a video game, so I'm fine with him too.(Sakurai was quite vague on the video game requirement for third parties. Plus, he's a fourth party, so...) We don't know if he could or could not viable. I do believe his words were debut, and technically, he did debut in the a video game. Before the movie released, he was playable in a demo, which is still a full game.(unfinished games do get released all the time, even if they're essentially demos) Basically, I'm saying that his wording is so vague that Ralph may or may not be possible. Yes, I am leaning towards "not happening", but I know his chances are 100% depending how Sakurai views that particular special situation.
Snake isn't as big of a deal simply because he isn't a huge Nintendo-orientated character like Sonic is now and the reason he was in simply for Kojima's kid to play as him. That time has passed, so him being switched out doesn't bother me that much. If you're wondering, I would prefer him over a Belmont, but I don't cry tears over him if he's gone. Now, I would have a bigger issue with a Shiek, Lucas, Jigglypuff, or Zero Suit Samus cut. They're actually an important character to Nintendo and Smash in general.