I think it's kinda dumb saying 'Not happening because of this character' as we all know how that went this time around
Honestly, I think it's different than people who were saying crap about the ESRB leak because of Dark Pit or Duck Hunt Duo or whoever it was that people thought "this leak is fake because those characters would never get in". 1st Party Nintendo characters are COMPLETELY different than 3rd Party characters. We have no precedent for anything but the top 3rd Party video game characters being added to smash. But we'd previously had precedent for clones and retro revivals.
Outta curiosity, which ten do you have in mind? Does that include Sonic, Mega Man, Pac Man, Ryu and Snake?
Even some of these are pushing it, but (no order on these):
Snake
Rayman
Tails (If Tails ever got in then I could possibly see Eggman get a spot on this list)
Leon/Jill/Chris (I'd air on the side of Leon as his games were more Nintendo-central)
Banjo-Kazooie*
Heihachi*
Spyro
Mickey
Bomberman
Simon
*Previously considered. (I may have forgotten someone, that's all I can think of from the top of my head)
Those are all characters who are relevant to Nintendo in one way or another, and I think there's each a reason to believe that they'd genuinely be on the 3rd Party radar. Obviously some of these do have some bigger hurdles to overcome than others though. I do think there's a possibility for some form of a SE character but I can't really think who would work. FF is such a huge series but I'm not sure there's any one character that could really fit the bill (as Cloud's game wasn't on a Nintendo system).
I know some people will vehemently disagree with my list, and that's fine. It is just my perception on the matter after all. If Shovel Knight does somehow make it into Smash, I will of course admit I'm wrong.