As I see it... In a hypothetical Smash 5....
Stays. End of discussion.
Sega is easy to work with. As is Platinum Games. Nintendo has a huge part in the series now and was included by winning the ballot. Only issue is that she's not very kid friendly, but they got her to work anyways. I feel her lack of pedigree may hurt her but the ballot is a strong point in her favorite. Likely to stay. She may never get another game but I feel the ballot makes sure that won't be counted against her regardless, no one has been kicked out due to lack of recent titles. I suppose there are complaints of realism but eh.....
Namco has always had good relations with Nintendo. Will always be relevent because it's ****ing Pac-Man. Now that they have used him. They'd be idiotic to not use him. Again, it's ****ing Pac-Man. No one will not want him. Likely to return.
Will never stop being relevent. Capcom has never been on bad terms with Nintendo and neither has the Street Fighter series despite its prominence on other consoles. Not much going against him other than potential directors not liking him or unpredictIble events. Has no real reason to go. Has a few complaints of realism but those are rather unfounded. Likely to return.
Again Capcom and Nintendo are cool. Was included due to massive requests despite lack of recent titles and the creator leaving. No real reason to go as that would cause an amount of backlash almost as big as Sonic's potential removal. No real reason to go. Synonymous with Nintendo. Likely to return.
The most hard to predict. On one hand, Square Enix is a ***** to work with. On the other end, and I don't think people stress this enough, they said YES. The actually let another company use their IP. And not just any IP. Their pride and joy and that IPs's poster boy. That is momumtal is itself. Just goes to show how big Smash is. Square and Nintendo have had a shaky history but they've been patching it up in recent years with both companies making great gestures towards each other. I only see their relationship improving from this point on. Cloud admittedly is more synonymous with Sony and Playstation, but it seems Square doesn't think he has to be. Plus Final Fantasy as a whole isa big part of Nintendo history. I feel that he would have more content if he was a Vanilla fighter but eh, water under the bridge. I can't say with certainty but I feel he can make it. It say it's close to 50/50 but more likely than not.
Snake. Buddy. What the hell happened? You had a chance before but Konami's dickbuttery has destroyed your chances moving forward unless your IP gets saved from their evil clutches. Now that aside. We don't know why Snake didn't return. Too mature or realistic? Bayonetta and Ryu seem to counter that. Moreover, Snake was included in the first place. Raising the rating? Maybe but I'm not too sure. Bayonetta made it in and other games has included realistic weaponry with an E10 rating. Even firearms. Did Konami say no? I'm not sure. Kojima said he was never asked but it's possible Sakirai went to Konami first and got shot down. Was it Nintendo? Again maybe. Apparently people didn't like Snake and Sonic in Brawl but due to the large growth in Third Parties I'd say they don't have much power or stopped caring. Did Sakurai stop caring? I don't think so. He liked Snake and valued his inclusion. I just don't know why he was cut. It is the biggest mystery Smash has ever had. I hope Sakurai talks about him soo. Regardless, Snake is synonymous with Playstation but got in Brawl anyways when Nintendo seemed to care about that more. He's gritty and realistic so complaints about that aren't unfounded but I'm not sure how much weight they truly hold. Konami historically has liked Nintendo but the new president seems to hate all console gaming like a poopmeister. Still, the Mewtwo effect is going strong and he is very requested and will be in the future. Possible but I doubt it. Love to be wrong though.
Personally, I want them all back as they all bring so much to the table and I'm against cuts. I also think the Smash 4 cast will stay due to an Ultimate style port for the NX, so.... Make of that what you will.