I've just watched the entire video and I must say that it was complete rubbish.
(Wall of text approaching. Sit down and get comfy.)
Since Marth has been announced and our worries have been laid to rest, I won't even bother talking about their idiotic reasoning as to why he'd be removed. All that I'll say is that Marth is literally the oldest representative of Fire Emblem and is one of the more cherished characters introduced in SSB. Considering the likes of Mario, Link, Pikachu, and Samus are allowed to stay, it would make absolutely no sense for him to be removed,
Ike will likely make a return, simply due to PoR and RD being fairly well recognized as the better of the console Fire Emblem games and the fact that Ike is as well liked (or moreso) as Marth.
Also, Lucina would be a poor choice to add to the roster (Though, I'll admit that I do think that based on personal bias. I did not like Lucina that much.). Chrom being added would be nice, but not as a replacement for Ike. Also, having both Chrom and Lucia in SSB4 is a tad redundant considering that they are both from the same game, Fire Emblem: Awakening.
As an added note, my brother thinks that if both Ike and Chrom are in SSB4, they will appear on the different versions of the game rather than on both. Ike would be on the Wii U, since his games took place on consoles (the Gamecube and Wii respectively), and Chrom would be on the 3DS, since his game took place on a handheld console. I could actually see the same happening for Marth and Lucina as well.
Removing Lucas?... Considering how much screen time I've heard he's gotten in SSE (I can't quite remember just how much he got, but if memory serves, it was quite a bit.) I doubt that they'd let go of a character they put so much into making. Mayhaps they'd give him a modified moveset (Just something to set him apart from Ness a bit more than now), or something, but I just don't see them removing him. Also, the Mother fans would be in an absolute outrage because of it.
Lucario being removed might be the most likely choice, however, I doubt that Mewtwo would replace him considering the fact that if they did put him back in SSB, he'd more than likely be Mega-Mewtwo X or Y. In Lucario's defense, though, I can't really say that you could replace his play-style, since it is something unique to him and him alone and removing him would be removing something that many people enjoyed using. Basically, they'd be pulling a Mewtwo again.
Rob is a very important remnant of Nintendo's past, he's as important to their past as Mario and Mr. Game & Watch. The chances of him not appearing in some form in SSB4 are very, very slim.
I... honestly can't come up with a reason as to why Wolf would not be removed. I'm not going to join in on the "Kill the clones!" crusade, but please, if someone can come up with a good reason for why Wolf will not be removed, I'd be overjoyed to hear it.
Pokemon Trainer... Will appear in some form, be it as looking a bit like Red,(Origins Red), Silver, Gold, Pearl, Diamond or, etc. S/he will be making an appearance because Sakurai, for all the stupid things that he may do at times, would not remove such a creative/unique play-style from SSB nor would he shun the fans of Pokemon by not having him/them return in some form.
Toon Link is back, there was no chance of him not coming back. Moving on.
Snake... This one I'm not sure about either. He was one of the better characters added to Brawl, yet the company that he hails from may not want him in SSB4. I can't really say as to whether he's safe or not.
Hopefully I'm not overlooking some aspect of why someone may return or be cut.
