There are plenty of different companies who would need to sign off even on things like a new Kirby or Fire Emblem character.I don't buy the whole "majority 1st-party pass" thing.
Mostly because it doesn't add up with Sakurai's comments about the difficulties of "working with different companies" during the development of the pass. I can't imagine there'd be that much inter-company work if the majority of the pass was 1st party characters.
HAL: Kirby
Intelligent Systems: Fire Emblem/Advance Wars/Paper Mario/Pushmo/Rhythm Heaven (also owned by Tsunku)
Itoi: EarthBound
Monolith Soft: Xenoblade
Let's say they include Paper Mario, Rex & Pyra (for tie-in purposes) and then a long requested character like Waddle Dee. You still need the companies that develop those series to cooperate.
Plus, to even sign off on including a straight up Mario character there would be meetings, which would be held up by Corona Virus.