Nintendo has confirmed Princess Peach will return for the next entry in the Smash Bros series.
An image was posted on the official Super Smash Bros Wii U websiteand is a closely cropped shot of Princess Peach fiddling with her crown.

Series creator Masahiro Sakurai is serving as producer on the new Smash Bros, which is a Wii U/3DS crossover being developed in partnership with Namco Bandai.
Thus far Nintendo has also confirmed a Pilotwings stage will feature in Super Smash Bros 4 and Captain Olimar from Pikmin were revealed as returning characters.
The first Super Smash Bros Wii U trailer revealed Capcom's Mega Man and the Animal Crossing villager would be playable for the first time in the series, and Wii Fit Trainer will also make her Smash Bros debut in this game.

http://www.computerandvideogames.com...ach-to-roster/