Citing sources inside Nintendo, Let's Play Video Games reports that Koei Tecmo, the makers of Hyrule Warriors, pitched a Star Fox themed Warriors game in early 2016. Like Hyrule Warriors, the game would have focused on melee combat, but would also feature simplified space battles. Nintendo reportedly rejected the idea "due to questions regarding the future of the brand."
I for one would have bought and enthusiastically played such a game, in spite of the relatively weird mashup. Stranger mashups have worked in the past. More importantly, Krystal would have certainly been a playable character! Oh well, we'll just have to see where Nintendo takes the series next.