There are plenty of skins that's based on other video games, anime, cartoons, etc. While not a carbon copy, the theme and idea is there. Think of it as paying tribute or homage.
Xena: Warrior Princess Sivir
Sailor Moon: Star Guardian Lux
Mortal Kombat's Scorpion and Sub-Zero: Yellow Jacket Shen and Frozen Shen
Nintendo's Bowser: King Rammus
Hellboy: Demon Vi
DC Comic's Poison Ivy: Zyra
Marvel's Storm: Tempest Janna
Adult Swim's Robot Unicorn: Arcade Hecarim
So... if they make a skin line of the Nintendo princesses, maybe some elements would be used but not entirely. Just imagine Karma wearing a pink dress similar to her Sakura skin but with peaches design on the dress. That itself could be an homage to Princess Peach.