Sit down everyone it's story (rant) time.
A long time ago in a galaxy far, far away, a game was released with two mysterious sword bearers. One of these lords had hair of majestic blue while the other had hair of flaming red. These lords, Marth and Roy, became loved by all they came in contact with. But as the ages past more lords began to rise up along with Roy and Marth. One of these lords, a blunt blue-haired mercenerary who always spoke what was on his mind rose up and gained the love of the people, even more so then Marth and Roy. Then came time for a new game to be released, one with more contestants than ever before. The mercenary, Ike, was the first to be let in, and Marth soon followed, being the first in the lineage of lords. But Roy was placed on the back-burner. While his techniques and abilities were finally being discussed though, a strange animal walked in. It was a hedgehog, with majestic blue hair like Marth and Ike's. The game makers fell in love with this pet and made a hard decision, one to cut Roy and another former contestant, mewtwo, from the game. Both Roy and mewtwo were broken, but mewtwo had something that Roy did not, initiative. Mewtwo left Roy and began to reform himself and go on new adventures, just to make the crowd fall in love with him again. But Roy did nothing. He watched as both Marth and Ike were clad in new armor and went on new adventures to gain even more love. He watched as the blue creature was obsessed by millions. He figured it must've been the curse of blue hair. But little did he know that the fans of the game missed him. They wanted Roy back more than anything. But through all of this things happened that made Roy feel even more dismal. Another hero arose, this one saving the lineage of lords to sure destruction. He was cool and collected, loved by many, and of course had majestic blue hair. But through this Roy found new determination. He clad himself in new armor and went to help this new lord, Chrom, on his journey, but not without a price of money of course. He hoped that his revival would lead to another adventure for himself. But the new game was arriving sooner than any new adventure to take place. He went to the stadium to find the list of contenders and scanned it closely. Marth was the first name he found, soon after he found his old friend mewtwo, and then that blue rat, sonic. Ike was next, followed closely by Chrom. He feared he would not be included but then he saw it, right near the end of the list, ROY! But why was he included? Here's why.
Marth will be included because he is the face of the franchise and has starred in 4-5 games whether or not you include awakening. Ike will be included because he was featured in two games, and is the favorite lord out of all of them. Chrom will be included due to being the Protagonist of the game that not only sold magnificently and got amazing scores, but saved the franchise from sure destruction. Roy's case is a little bit more tricky. I think he will be included as a character somehow, my narrative made him as a late inclusion. I think this will be the case because he really isn't very influential when it comes to fire emblem, but he has the credentials of being the second most missed character in brawl besides mewtwo and has huge popularity, usually in the top ten or even 5 in polls. So I think sakurai understands this and will make him a late inclusion Marth clone just like Melee, or he will be a DLC character with either his Melee moveset or a new one, who knows.
As for why fire emblem itself deserves 4 reps there are plenty of good reasons. First of all there are 13 different fire emblem games. That is a LOT. Second of all they are some of the most popular Nintendo RPGs out there and more popular games tend to get more characters, unless they aren't very character based. This doesn't exactly work for fire emblem though because fire emblem is the most character based game ever. I am not even exaggerating on this one, there is no game in the universe that is more character focused than fire emblem, that's what makes it so awesome. And lastly they have 4 perfect characters to include in the roster, so it's not exactly hard to pick.
So yes, fire emblem deserves 4 slots. But do you know what fire emblem really really deserves? It's own goddamn fighting game!!
Also sorry about the narrative I got carried away.