I'm still disappointed by the Hyrule Warriors roster, since it's missing a considerable amount of characters. Tingle, a series staple, should've been in in some form, and the entire "Celda" sub-branch was completely ignored, save for the Wind Waker weapon which, strangely enough, only plays songs from Ocarina of Time. It's disappointing that less than a quarter of the Zelda series is being represented properly.
I know they brought up the possibility of a sequel, which I would be all for. Hopefully they could add in some Wind Waker environments like the Forsaken Fortress or Dragon Roost Island, and bosses like the Helmaroc King and Molgera. Characters like Tetra, Makar, and Medli would be wonderful additions. I don't even think the art style would be too jarring if they didn't want to change it (I personally find Cia to not fit in with the series at all).
And I think a Four Sword weapon would be awesome.