The criteria is as follows for who gets the updated lore first:
- Are they a new champion (e.g. Illaoi)
- Are they getting a big rework (e.g. Gangplank, Fiora and soon to be Poppy)
- Are they going to be involved in some kind of story or event in the near future (e.g. Graves, Twisted Fate, Miss Fortune, Hecarim, Thresh...)
- Are they in the category of "I'm not canon right now" (e.g. Singed, Malphite, Kayle, Morgana...)
So basically it's on a case by case basis right now. At the moment the current scheme of things is that Poppy and Taric are the big VUs that are being worked on, with Poppy right around the corner, thus they're getting new lore done for them. At the same time we're gonna be going back to Shurima soon and Mount Targon after that for some kind of story, so the cast of Shurima:
)
And the cast of Mount Targon
Are in line for updates too. Then we have the champions who aren't actually canon currently and have what is effectively no lore right now, and I'm not talking about having a single paragraph like some champs still do right now. I'm talking about folks like:
Who all fall in to the camp of being non-canon at the moment to varying degrees (Folks like Nautilus, Orianna and Lee Sin need some tweaks and they're fine, where as Malphite and Jax kinda don't exist at the moment. These guys are also being treated a bit different as where the other guys, be it new champs, reworks or event included characters are made for a deadline, the guys who have broken lore are on a "It's done when it's done" basis, so when they're pleased with what's been written that's when they'll release it.
Hopefully that explained things in an alright fashion.