If there were any second Square character to be considered, it would be Sora and Geno since their demand is very high. The former choice feels like something Square Enix and Nomura (Who has close ties with Sakurai now) would love to add. I do not see anything else helping Lara's chances if developer connections are not present or if the requests are not high.
I mean, there’s more at play than “they’re highly requested”.
If Nintendo is going to negotiate for a character, which would they rather have? A video gaming (not just Nintendo) icon or a niche character from one game? They’re spending money, time, and resources into getting the rights to a character for Smash.
If anything, it’s Sora or Lara Croft. Geno loses out big time there. While he has popularity, he’s nothing compared to the gaming titans that are already in Smash.
To continue, say Sakurai goes to Square Enix to obtain another character. Knowing the possibility for advertisement and news to generate for themselves, does Square advocate for two games that have quite a bit of hype surrounding them (Shadow of the Tomb Raider, Kingdom Hearts 3) or a one-shot character from a SNES Mario game they developed? The choice is obvious, and it’s either one of the first mentioned.
You also make it seem as if whoever Sakurai has interest in, he gets. This implies that Disney would be entirely willing in any capacity to allow Sora to be used. There’s entirely the possibility that they aren’t.
Also, you only mention popularity with 3rd parties. Ryu wasn’t really requested for Smash compared to several others, yet he’s in the game. Don’t put all your eggs in one basket.
EDIT: Now that I think about it, there’s also the Sakurai quote where he says he doesn’t want to add 3rd parties “willy nilly”. So far, the quality is high. Now he suddenly adds Geno? A one off character who happens to be popular?
I like Geno as much as the next guy, and I think he’d be really fun. Hell i’d be excited to see him in Smash. But let’s not act like he’s incredibly likely or something.