I think Hilda's chances are bigger than what people are thinking.
I can use Dark Samus as an example, before echoes were a thing, she wasn't that popular, people were asking for Ridley, Rundas, Sylux... yet, Dark Samus got in, why people start assuming she was in? because Samus was missing her "Dark Samus" alt, which is curious, because Zelda also doesn't have a Hilda alt.
Then we have the thing that Hilda could be consider a villain (even if her motives where good), and this Smash seems to be more oriented to villains (with Ridley, K. Rool, Dark Samus and all the rumours of Skull Kid).