There are currently 55 champions in the pool for TFT and currently 25 Project Skins. Only 3 of these Project champions are not in the pool. Can we use the project skins for all players for the 22/55 TFT champions that are in the Project Lineup instead of the Classic or oddly chosen skins being currently used? This would be awesome!
They have currently set it so you can't use skins on purpose. It gives them a method to introduce different origins/classes for the same champion.
E.g. Cutpurse TF is currently set as a Pirate/Sorcerer using Pick a Card . If they used Musketeer TF instead, then you probably would get a Noble/Ranger using his E and will be manaless.
Next split (around 3 months time), they plan on rotating out the current sets of champions and introducing new sets of champs with different origins/classes with the use of different skinlines. Riot did mention that they would want to use skins from the project universe (project, battle cast, program) and odyssey universe (Oddessy, dark star, cosmic).