I think it's worth noting that it is very rare for Sakurai to outright plan to not have a character return.
In Brawl, everyone was planned to return from Melee except
, who had a functional replacement that was more relevant at the time, and
, who was a gag character and may or may not have had a functional replacement planned (depending on how you interpret Pra_Mai).
,
, and
were all cut mid-development.
In Smash for Wii U/3DS,
were planned but cut mid-development due to the 3DS' hardware limitations. We also know that transforming characters were cut due to the 3DS' hardware limitations, so this was presumably what did
and
in. The Gematsu leak alleged that
was cut late into development, but its debatable how true this was (the leaker didn't know Chrom and the Chorus Kids were cut, but did know Lucas was despite this decision being made later in development?). The reason for
's exclusion is kind of unclear, but internal politics between Kojima and Konami is the typical explanation and it fits with Kojima going out of his way to initially get Snake in the series. That just leaves
, but it's safe to assume he was also cut due to time constraints given the lack of a functional replacement, rights issues, or technical concerns with his moveset.
My guess is the next Smash will follow a similar suit and
try to do "Everyone is Here!" again, albeit with the condition that this lofty goal likely won't be reached and who is in by the time development ends is in.
For Nintendo characters, it will likely be a matter of priority like we've seen in the past. Each character will be given a relative ranking and will be worked in that order. For example, if
is ranked 30th, at least 30 Nintendo veterans will need to return for Ike to be in the base game.
For third parties, I really think that is just up to whether licensing deals get off the ground. Nintendo and Sakurai will likely put in a reasonable effort to obtain them, but it will all come to down to whether the owner of the character plays ball. Once the rights are obtained, any third parties will probably jump to the top of the priority line in the interest of making things simple legally.
In terms of the number of veterans, my guess we'll get 54 at least and 64 at most. Ultimate was able to bring back 59 characters from Smash for Wii U while stretching the Smash team, so I'm taking that figure and giving a range of +5 to -5. Echoes might skew this figure a bit, but any smaller than 54 seems like too much of a step backwards and any larger than 64 seems too unrealistic.
