I feel like what would be a great explanation as to why we still haven't seen Alice's descendant is that after Wonderland, Alice & her child become adventurers and head to distant lands, just like the main cast.
Another announced character who was ultimately cut was Zellie, a teen version of Rapunzel. Her scenes were completely removed, and she was reduced to a background character named Meadow.
The Miraculous creator speaks on why there is no Fortnite collab
"The sticking point is that in Fortnite, weapons are used and other characters are 'killed.' A level of violence that is not compatible with the image of our characters."
(Noticed by @BackersGamesF)