I know they won't be because Porky faces the hardest challenge such being from a dead and small first party series which makes people believe that his absence is not very jarring since the Smash team just doesn't care enough to put him in as a spirit. I mean they're right about Mother being a small series not much people would care about. Despite being one of the never evers, Sephiroth was very popular and his inclusion is justified being from a relevant series and the missing FF7 content aged like fine wine.
Porky is from a dead first party which is a different situation compared to dead third parties like Banjo and Kazooie whose games were major successes in the past while EB had flopped. As we have seen, all first party choices were promotional picks of recent titles on the switch. There has been no legacy nintendo dlc candidate for now. If a character is from a dead first party series like Mother, it is hugely unlikely they'll be a dlc candidate especially with Nintendo choosing the DLC.
The Sora leak actually has some credibility. It correctly predicted the date October 5.
Just because it gets the date right doesn't make it credible; there's a three month window between now and the absolute latest time that the second Fighters Pass is supposed to be finished by (December 31st, 2021). I'm not sure when this supposed leak was posted, but given that Nintendo's consistently had a Direct every three months, and both Directs and Smash presentations seem to consistently happen between Tuesday and Thursday, it doesn't seem tough to pick a Tuesday, Wednesday, or Thursday in September or October and wind up with the right date.
If there were screenshots, or a detailed description, that would be somewhat credible. If there was video (unlikely, but it happened with Smash 3DS and the ESRB leak), that would be even more credible. As it stands, it could just as easily be a lucky guess.
(then again, I thought that it was a coincidence that the reveal that wound up being Steve happened shortly before MineCon, so what do I know?)
EDIT: also,
the person who was seemingly behind the "leak" admitted that it's fake - it's a Twitter thread containing screenshots from 4chan, so there's some crude language in there, at the very least.