Alright, got Artsy's comment right here.
"Sorry, but 100% (I'll concede that it's more like 95%) of this is reaching. =P none of this actually points to Shantae being in Smash. It's just a collection of coincidences and observations that can merely be construed to relate to smash but aren't inherently relevant. The only reason they were vocal during the smash ballot and not now is because there isn't a smash ballot for this game, so there's nothing to campaign for. But I get it. It's just for fun. Just.... don't get your hopes up. You'd only be setting yourself up for disappointment. Sorry if this is blunt, but I'm just being real. I like shantae a lot. I just don't see how any of this actually indicates that she's going to be in Smash. " Artsy Omni
While I would say that a lot of the Jammies Mode information is a bit reaching (not completely dismissable, but its tricky to use it to prove anything), the possibility of an NDA is possibly the strongest part of it, on top of the Shantae trademark coincidentally occurring very close to the roster finalization.