So I'm going to try to keep my thoughts as organized as possible here, and by no means is anybody required to believe anything/everything I say. This is merely one dude's thoughts on it. You're free to disagree, and I'm not speaking as though my thoughts are infallible. I feel as though I've been accused of this in the past, so I'm prefacing my post with this now. This will be based on as much factual observation as humanly possible.
The Debrief
Obviously, the lead up to this reveal was a 3-month ongoing debate about who the character would be. It was very easily boiled down to 2-4 fighters, however I think it's pretty clear it was between Spring Man or Min-Min for the fans. We get Min-Min as playable, with Spring Man maintaining his Assist Trophy only position. I'll speak more to that specific point in a bit, but I think there's a lot to be excited about. Spring Stadium looks fantastic, Min-Min looks fun to lay (though I'm not sure how well she will do competitively) and we only have to wait a week. For much of the remainder of this post, I'm going to gloss over a few points I have made, or have observed in the presentation.
#1: My point on "mascot OR protagonist first"
For much of the last 3 months, my position was that I expected a Spring Man upgrade because he was the "mascot" of ARMS. With Min Min entering Smash instead, that point seems to lose steam...unless you think back to what Sakurai said in regard to that specific point and in relation to the interaction with the ARMS dev team.
Today, Mr. Sakurai said, "Many of you might be thinking that Spring Man is the protagonist, but that doesn't seem to be the case. Mr. Yabuki said, "Everyone is the protagonist!"
Yesterday, I mentioned a potential Monkey's Paw in which "Min-Min would be considered the 'new mascot' of ARMS". This would appear to be a Monkey's Paw, just a tad different. To the developer of ARMS itself, and evidently to Mr. Sakurai, every character was "a" protagonist of ARMS, meaning none of them are "less than" another. It's simply that Spring Man and Ribbon Girl are on the cover.
It doesn't really matter what the fans think about the protagonist "rule". If you ask me, this solidifies it pretty firmly. They chose the character and consider her an equal protagonist to any other character...that being Spring Man, or Master Mummy, or Kid Cobra. There's nuance to the pick, and I will get to that in a bit. Even though it's a Monkey's Paw, Min Min still fits the protagonist rule due to the viewpoint of Mr. Yabuki (ARMS Director) and Sakurai.
Call me biased, but this is my perspective: Even though it was Spring Man, we still got a protagonist, meaning this strong is still significantly strong AND measurable when you observe Smash's roster as a whole.
#2: Spirit Upgrades
Min-Min is obviously a spirit in Smash Ultimate, prior to becoming a playable character in ARMS. Much to the happiness of many fans, this now brings a potential outcome for other spirits to join the battle, which was previously seen as unlikely. Whether that comes to pass, we'll just have to wait and see, because there isn't enough evidence to suggest we'll get additional upgrades, but that's simply because of the evidence we currently have. It can happen, but will it happen again? That depends on the character, I would say. It also depends on what else the character is represented with in-game. Is it just a Spirit? An Assist Trophy? A Mii costume? Things can be blurred pretty quickly, especially considering the Smash fanbase has more or less lumped Assist Trophies and Spirits into the same NPC category, but I think it's time we take a step back and really look at them as two very different things. That said, next is a significant part.
#3: Spring Man Assist Trophy Out to Dry
Spring Man is on the cover of ARMS. He's a basic character, and is function is fairly well shown in Smash Ultimate as an Assist Trophy. That said, many of us expected him as the "mascot" or "Protagonist" of ARMS. This was clearly sidestepped with the caveat that all fighters from ARMS are protagonists, with Min-Min likely being selected because of her popularity, but also more firmly because she was Mr. Yabuki's "favorite".
When Sakurai talked about who he was thinking of with ARMS, he specifically mentioned Ninjara and Min-Min. He didn't mention Spring Man. We can have an imagination as to why he didn't look at Spring Man, but I personally think we can infer that it's because, well, he's an Assist Trophy.
With that being the reasoning...that doesn't bode well for Assist Trophy upgrades. Many fans looked at Spring Man as a key move to put Assist Trophies back on the table, but that's not what happened. While a character that had no previous presence in the game, such as Max Brass or Dr. Coyle would have likely shut down a lot of discussion about upgrades, Min-Min being the addition appears to put Spirits in a decent position (assuming she isn't an exception, which is yet to be seen). That said, I think it matters if a Spirit was in base game vs. post-launch content. I feel base game spirits have a much better standing.
However, it's my humble opinion that Assist Trophies are off the table. This unfortunately knocks Waluigi, Isaac, and other picks out of the running, which shapes speculation at least a tad differently.
#4: Heihachi and Tekken
A sad moment hit today when Heihachi and Tekken were struck down from contention for Volume 2. This comes as a potential surprise for some, with such a massive character and series not receiving the playable status some wanted. This is a relatively interesting disconfirmation. It strikes down a well known character, but we still have yet to see Lloyd Irving's costume return. While it doesn't mean he can't be revealed in the next video, it's interesting that he's missing.
I would love to see Lloyd myself because I really liked Tales of Symphonia, but I'm hesitant to say the missing costume means the classic, "He's in!"
#5 Conclusion
To wrap this up, I think Min-Min looks absolutely amazing. I wasn't particularly attached to any ARMS character, but I'm excited to try Min Min out next week. I'm happy for the ARMS community and fans who really wanted to see her added.
In terms of what we talk about here, I think this Direct changed things. In my humble opinion, Assist Trophy upgrade candidates that folks talked about aren't looking great right now. We all knew Spring Man would be used as a potential ticket to that being a mainstream argument, and I don't blame people who desperately wanted Waluigi or Isaac to be in the game. However, I think it's fair to say this Direct changed things.
That said, looking to the future I feel it's safe to say that any series being introduced to Smash will begin with the protagonist or "a" protagonist. ARMS is unique in that it's a young fighting game with no story, where every fighter can take on the Grand Prix. Mr. Yabuki said himself that Min-Min is a protagonist in the same way that Spring Man, Kid Cobra, or Mechanica are protagonists. It doesn't seem like a fan rule to me, it seems like something that was backed up today by Mr. Sakurai, and is further backed by the Smash Ultimate roster we have today.
I believe Spirits are on the table, but to what extent? We know in reference to "publishers" (in a separate clause from Nintendo, meaning we're looking at Nintendo + two other publishers) that we're looking at, I would say at least two 3rd party fighters, leaving 3 spots open to more 1st party fighters. I'm not convinced that upgrades will play a major role in Volume 2, though I won't rule them out entirely
I hope I didn't bore anyone with this "debrief" but I'm glad I finally got my thoughts out there. Thanks for reading!