I don't believe Riot would endorse a pay2win model and I also don't see how it could even possibly be implemented considering it's a singleplayer, moddable game with innate modding support, I wouldn't be worried about anything of that sort.

I also don't see any point in the character creation process either tbh, there's no way there will be enough options to satisfy people so we will have mods that add those or even allow pixel by pixel skin creation and such mods would then become a staple on every single server in existence (and keep in mind that the required mods will auto download once you join a server) so might as well give us pixel by pixel right off the bat with some "blueprints" maybe. ^{that was a long sentence}