I think they will definetely use her Gold design as the base. Ware characters in smash has always been updated,
KatAna´s assist trophy was changed from SSBB to SSB4. Also Ashley´s assist trophy has red eyes now in SSBU and
not black ones like she has in SSB4 and Game&Wario. They also use the Mona in her original and her touch design
for the stickers in Brawl, but changed it to her Game&Wario design for her trophy in Smash 4. The stickers on the
Gamer stage has been updated as well.
It would be weird if they use her old design as a base, after all they would want to use a second Ware character for
commercial purposes as well, also I almost see only positive reactions to her new design, with a few exceptions.
My guess would be, that they use her Gold design as a base, but they make her a bit taller (since Wario´s smash model
is also a bit taller then his Gold design). But it would be cool if they give her a skin of her original clothes
.
Well at least I would make these kind of decisions if I were Sakurai.