Depending on who you feel is going to be in the first game, who do you think is going to be DLC
The ones I see are: Banjo, Isaac, Skull Kid, Dixie, probably some new characters I don't know about
Shot in the Dark: Sora
My assumptions for the base game at the moment are Banjo & Kazooie, Geno, Isaac, and Incineroar. Given those:
I do not actually think
Rex & Pyra or
ARMS rep are locks--because it's Sakurai, there are no locks. But with every veteran in the base game, unless Nintendo goes all third party (unlikely), I feel like they're pretty likely.
Third Party wise, I believe we'll see characters from our current third parties.
Dante is very likely as Capcom's next rep, and with Devil Make Cry 5 coming out, it's highly relevant and we've seen increased popularity recently. Bandai Namco is another question mark--rumors that a character in the base game, and I'd think Lloyd would fit in that case, though I think
Heihachi would be a fit for DLC as he was once considered and could be a Ryu situation, with a fighting character for DLC. I think a Persona rep for Sega/Atlus is a big possibility, and as Sakurai liked Persona 5,
Joker would be the likely representative.
Sora seems the most likely actually, his popularity larger due to Kingdom Hearts 3 (which was still very large in 2015), and fits Smash well. And like B&K, those who own the copyright (presumably Disney, Square less so) have been rumored to say they would support his inclusion if Sakurai asks (but both Disney and the creator must agree). Whether this includes Disney content included somehow--I would guess probably not (but I would love that). And for series not currently from a third party in Smash, I think Activision's
Crash Bandicoot has the highest likelihood--a mascot character with a Smash-perfect moveset, who's back in the public's consciousness thanks to the N-Sane Trilogy. And it would just be cool to Sony's former mascot alongside Nintendo, Sega, and Microsoft content.
Other first party characters--if Skull Kid and Bandana Waddle Dee do not make the base game, it's possible they could be in the game given their huge popularity. But I'm much less certain about them, as they also have a high chance of making the base game for various reasons. My bet would be on
Skull Kid. As much as I would love for assist trophies to become DLC characters to make it so assists are no longer a hard deconfirmation, I have a feeling that's too pie-in-the-sky. I would prefer Bomberman, though if anyone has a chance, given Nintendo officially commented on the matter through Reggie, Waluigi is perhaps the most likely candidate.
So I'm thinking:
1.
Rex & Pyra
2.
ARMS rep
3.
Skull Kid
4.
Crash Bandicoot
5.
Dante
6.
Heihachi
7.
Joker
8.
Sora
I also see echoes as a possibility given how easy they are to make and can satisfy fan demand. But I'm less certain of who, given I haven't thought about them as much, other than Octoling--but they too have a possibility to be in the base game, depending on what time frame they could be made in. Also, this is all heavily biased--they're all characters that I know, and many I have a preference for (seen in my sig). But I've tried to be fair, for instance as much as I want Tails, I think it would be better to see a new series like Persona be represented. And, of course, this is all tentative because I still think they're waiting for the game to be finished before working hard on the details, even though they may be considering it at this point, and who knows where the zeitgeist will be when the game launches.