Basically the title. I think it would be very fitting for Faker to get a legendary skin. The legacy he has behind him and being the face of LoL Esports for almost a decade he deserves to get a legendary skin for a legendary player.
Also given that the SKT skins were released in this price order it also fits:
2013 - 750 RP
2015 - 975 RP
2016 - 1350 RP
2023 - 1820 RP
Faker was the only one in all of the winning rosters and just by his status alone he would be worthy of a legendary skin.
Either A) on his 5th title or B) when he retires.
I think it would mean a lot more to memorialize him when he retires. Heck a permanent champion would be even better (start developing now Riot). Like, you shouldn’t retire a players jersey before they finish their career, it would be a nice hopefully unexpected present.
I know it sucks for all of the other pros to not get anything. But there is no denying how much Faker has done in the game.