Here is what I believe the five DLC slots are:
1. Square-Enix character (Geno, Sora, or Dragon Quest character)
This is the one DLC slot that Vergeben knows about. However, its split as to who it could be. Geno has Sakurai's personal preference. Sora might very well be the most wanted third-party character not yet in Smash Bros. Dragon Quest is the biggest Japanese third-party franchise left without any sort of representation in Smash Bros., and there is an upcoming port of Dragon Quest XI coming out for the Switch.
2. Namco-Bandai character
It seems really odd that that Capcom (Mega Man, Street Fighter), Konami (Metal Gear Solid, Castlevania), Sega (Sonic, Bayonetta), Square-Enix (Cloud, whoever the DLC character is) would all have two series with playable characters in Smash Bros., yet the developer for Ultimate still only has one (Pac-Man). Moreover, many of these companies have their series represented through other content in Ultimate (Virtua Fighter has an Assist Trophy, Monster Hunter has a boss and an Assist Trophy, Bomberman has an Assist Trophy). Aside from Mii costumes, Namco-Bandai has no other significant presence in the game aside from Pac-Man. I think the second Namco-Bandai character will probably be Heihachi or Lloyd. However, its always possible that they go with someone else from Tekken or Tales. It is also possible that someone from Soul Calibur is selected.
3. Banjo-Kazooie
Vergeben has gone on the record to say Minecraft content is coming, though he has not said what it is. Personally, I think we will be getting Minecraft content though it will probably be a stage and an Assist Trophy (there are six empty stage slots on the character selection screen, one more than the five slots that will be attached to the five upcoming DLC fighters aside from Pirahna Plant). Banjo-Kazooie did phenomenally well on the ballot. Microsoft has also expressed interest in the character being in Smash Bros. Microsoft owned characters (including Banjo characters) have also appeared as part of a Minecraft skin pack for Nintendo console ports of Minecraft, and crossplay for Minecraft between the Switch and Xbox was promoted at E3.
4. Bandana Dee
It seems really suspicious that Bandana Dee is among the few series critical characters not to be represented in any form at all in Ultimate. Not even as a spirit. My personal hypothesis is that characters being excluded as spirits are being saved to become DLC. Bandana Dee is likely going to be DLC due to his high important in Kirby titles released during this decade, as well as his very high popularity, particularly among the Japanese fanbase. He is probably the one Nintendo newcomer I feel the most optimistic on.
5. Elma
It is extremely suspicious that Xenoblade X has almost no content in Ultimate, to the point where Xenoblade 2 has far more content. The only piece of known Xenoblade X content in Ultimate is a spirit of a Skell. That is it. No music, no Mii costumes, no Assist Trophy. If Elma's spirit is not seen in Ultimate, it will be extremely obvious that she is being saved to become DLC.
These are my predictions at this time. I might revise them if it turns out that Bandanna Dee and Elma do have spirits in Ultimate. However, even if that is the case, I will still feel good about Bandana Dee's prospects.
The slot I feel the most iffy on is Elma simply due to the fact that the primary reasons that she is even on here is due to the lack of Xenoblade X content in Ultimate (only a single spirit has been spotted for X, while Xenoblade 2 has multiple spirits, three music tracks, and two Mii costumes). The game is going to be four years old in a few months (in Japan at least). It also was not received as well as the original title or 2, so its somewhat of the blacksheep of the series.
If Elma does show up as a spirit in Ultimate, then her slot opens up to Nintendo newcomers in general, of which Dixie Kong is a possibility. Elma herself would still be contender for DLC, however, she would merely go from a near guarantee to merely a contender. The hopes of many character hinges upon whether there are going to be spirits of Elma, Bandana Dee, and Pirahna Plant. If spirits are absent for important or highly requested characters, then its obvious that spirits are marks of deconfirmation and that it will be that two of our slots are going to Bandana Dee and Elma (and the other three likely third-parties).
Dixie Kong's fate (and the fate of many other characters shown as spirits but lacking any sort of notable NPC role in Ultimate) hangs in the balance with us knowing the whereabouts or lack thereof of these three characters.
If these three characters do show up as spirits too, it means that Dixie Kong has a shot at becoming DLC, and even has quite a few things going for her (her popularity, her legacy to a popular Nintendo franchise, the possibility of her being an Isabelle/Wolf/Lucas style character to Diddy Kong which could help facilitate her development). However, we will not know for sure until the release of the game.
As with for much of this period, Dixie Kong once again finds her fate in a state of ambiguity. Its ironic that she finds herself being among the few characters whose possible de-confirmation for this game will not be known about until the release of the game, the traditional de-confirmation point for character hopes.
We have less than four weeks left. There is nothing else we can do at this point. Talking about why we cherish this character, why we love the games and series she is from, and what we expect from her if she does ever get in, are all topics we can partake in the mean time.
I hope my post sheds some light on what the situation might be looking like for DLC. We are currently facing an uphill battle. However, keep in mind, most speculators told me Roy had almost no hope of being DLC back in November 2014, yet look what happened. Ultimate put in so many characters whose day we thought might never come as well as many characters whom we believed to be a shoe-in, not just for the base roster, but also for DLC, ended up being de-confirmed.
It could end up my predictions for Ultimate's DLC end up mostly being wrong. They could mostly be right (or even entirely right). Regardless, we will not know whether spirits are marks of deconfirmation until the game releases.
Who would have thought that the one piece of unknown content that I would be the most anxious to know about in regards to Ultimate's release would be this game's equivalent of stickers? Yet another example of how this game's speculation cycle threw so many curve balls at me.
I am once again grateful for all the (pleasant) surprises this game has given to me and many others. Now I am just rolling for one more miracle. Dixie Kong as a fighter in Smash Bros.