Legitimately asking, do the sales really tell the whole story though? I say this as someone who has bought ever single smash bros, this one is by far my least played (even though it isn't necessarily my least favorite). Like does the game have a legitimate following and get run time by a majority of those people. It may, but it fell off for me compared to previous entries.
Well no, sales don't tell the whole story, they rarely ever do. But I think the amount of Smash fans who are pro players and upset by some of the changes in Ultimate, aren't a large enough slice of the total customer base to have a material effect on changes for the next game.
UNLESS, Smash is one of those IP where the later casual and mainstream mass-market adoption rates are heavily reliant on early momentum set by hardcore and core enthusiasts (which would include pro players). If so, then lower purchasing rates at launch of the next entry could have a knock-on effect for latter adoption, though maybe in a subdued manner. I just genuinely don't know what percentage of the hardcore Smash fanbase align with pro players and the such on their problems with Ultimate, though.
Also, I do feel Smash is one of those franchises where casual/mainstream attention and those who take to it more as a party game, just treat it like tradition at this point. Kind of like those who always buy COD annually no matter what, or Madden, or FIFA/Football Club etc. Nintendo are probably more interested in appealing to the less hardcore demographic for the IP, but I would agree with the idea that they could balance it out with appeals to hardcore & pro players all the same.
34m copies sold but sadly that doesn't reflect the online player base today, which I think is what the video is talking about. Things are definitely winding down for Ultimate. This time last year I'd get a game in 20 seconds tops during peak hours, but now it can be a minute or more.
I don't know if Nintendo is going to do a brand new Smash 6 or overhaul Ultimate for Switch 2, but Ultimate is shedding players fast.
FWIW I don't think Nintendo really ever intends for Smash to be the type of game carried by an active online community. It's not a GAAS, per se, but primarily a traditional game with traditional multiplayer modes and some live service components like the online MP. In that sense it's closer to something like, say, GT7.
The vast bulk of Smash money is made on B2P sales and new character DLCs. And even those jaded by certain aspects of the game are likely to buy the characters, just to see what they're about and build up their collection of fighters for their roster.
Also while not necessarily dinging on playerbase drop-off possibly tied to changes in the game, well, it
is the Switch's 8th year on the market. A good chunk of people leaving the game could just be winding down their time on Switch in general as they take to other platforms for the time being, or wait for Switch 2's release and new 1P games with it, like the next Smash Bros.