Building off your point somewhat:
This is something I talk about in my upcoming article (need to do final revision after this post!), but you could make the argument that the best and the brightest Nintendo stars are, for the most part, already represented in the game. I think a third party character like Bomberman or Snake would easily trump most of the characters you list...with the exception of Inklings (who are very, very popular right now. Even my high school students are talking about Splatoon) and maybe Wolf as there are a lot of fans of Brawl (But, let's be honest...if he wasn't in Brawl then he probably wouldn't be such a strong contender for DLC).
After a certain point we are just treading into Nintendo's B-Star territory (Before someone brings up the clones,
there are a lot of misconceptions about clones). I know these are the fan favorites in the speculation community, but I've been saying for months that our polling
methods are very inaccurate and probably don't represent the bigger Smash community's wishes. Yes, that even includes the
polls I've conducted. I honestly don't think Shantae and SK would generate a lot hype outside the Smash community, which is why I keep going back and forth on the SK rumor. However, at least SK has a ton of cross-overs, and Nintendo is treating him like their indie-baby. I would honestly put the indie reps in the same tier as a lot of the Nintendo characters you listed,
True Blue Warrior
. Sure they have fans, but we need to remember that we are in a constant echo-chamber.