This will never happen simply because Riot is pretty selfish when it comes to customized experience. I mean, look at what Valve has done for DotA 2. They have announcer packs, UI packs, and even cursor packs galore! My in-game announcer is Kevan Brighting (the Narrator from The Stanley Parable) while Rick and Morty announce multi-kills and kill streaks. Some examples:
Rick: (on killing spree) "Killing spree, my ass!"
Morty: (on killing spree) "Hello? Can anyone hear me? It's a killing spree over here!"
Morty: "Hooh! Well, looks like we got ourselves a triple kill here, Rick."
Rick: "Morty, quit trying to act like a detective."
Rick: (on triple kill) "Riggity-riggity-rekt, son!"
I changed my UI to look like Ancient Greece (the Antiquity pack) and my cursor is a bright red color (the TI6 pack) to keep track of it more easily on screen, particularly in team fights when all sorts of particle effects are firing off at once. Riot simply doesn't do jack about custom looks beyond alt skins because they only really care about eSports. All that money they pull in gets fed mostly into the pro scene without much regard for the rest of the community.