Regarding AT/Spirits upgrades, I could see them... if those were the only options to choose from. One of the popular arguments at the start of the fighter pass was that it isn't possible that spirits disconfirm as there are 1300+ that would be disconfirmed, but when you look at it and the current pass they easily grabbed characters that weren't represented in the game and as long as there are options to choose from, they can keep adding as many non-spirit characters/franchises as they want.
I know that there's comparisons with trophies in Sm4sh but compared to the DLC back then, Ultimate seems a lot more planned and organized and the continuous addition of them just makes me think that people are taking their status quite lightly.
Remember the whole thing with the fanpolls, not every popular character is going to be shown in the fanpolls. So they can choose easily franchises that are popular and still have nothing to represent them on Smash yet. A popular character that is a spirit is not the only popular character in the world. And while Sakurai could surprise us, I really doubt it given the scope for the game and frankly I will keep the idea that AT/Spirits/Content is disconfirmation until it isn't.