Every Spirit event is now infinitely worse feeling. Every time a Tuesday rolls around, that sinking feeling that it could be THAT Tuesday, where the character you've been asking for for a long time now will be put to rest... yeesh, hope you don't get invested in the idea of a character making it in.
My general predictions still stand: Nintendo will do what they did for FP2 again. Popular third party with no obvious connection to Nintendo -> Huge Japanese character who was previously considered out of reach -> Western character of the same kind -> Iconic to the genre, niche in general third party with a huge legacy -> the new slot, a wild card -> A first party character intended to promote an upcoming (at the time of development; the game may release beforehand) release, who is widely unpopular in the Smash fandom.
I believe there is a chance we could see a Volume 3 anyway, but only if Volume 2 blows expectations out of the water. Like, incredible sales unparalleled in DLC before (I'm talking 80%, 90% of SSBU owners buying it, which is a complete farce and not going to happen). Otherwise, this is most certainly it.
Bear in mind, I will be happy to see a Spirit event in some cases; rejected Spirit candidates for Volume 1, Mii Costumes getting more Spirits, and other such things would be great. But any unrepresented franchise will be bittersweet at best, because while at least they're in, it means they won't be in.