How far forward do you look when choosing a champ for skin?

I noticed that Morgana is getting a Harrowing skin, and thought about other champs in need of skins. How far in the future do rioters look when deciding who gets a skin? Do they just look at who is on the table for a full VGU within a year and a half, or do they decide based on wether the champ is being reworked atm?