I feel like League's story has the potential support such a thing. With such big villains as the Void, the Black Mist, Darkin, and Xerath, I feel like there is a ton of ripe potential here for something huge to happen. It's a shame all this potential isn't being put to use. I feel like every Lore event so far has only tickled us with the potential that the League of Legends lore could potentially bring to the table.
They're propably never going to deliver on the massive lore cliffhangers we have because it just generates too much hype for lore enthusiasts.
Let's count out a few, shall we?
I know this is being a tease, which is my comfort zone (just ask Necrit and his gang of lore translators), but think less of these stories as necessarily being 'events' -- which have a variety of definitions anyway.
Will these all be 'Burning Tides' style events? No. Will they be lore bundles like Demacia, etc? Maybe, probably not. However, I think just about everything on that list is something that could be either a long-form story or at least a story that can be big enough to be its own thing.
I can't be specific, and I'm sorry about that, it's purely due to production reasons and respecting the work of different teams, but we want to tell the stories you mention, as well as the stories that build toward them, and the stories that lead on from them.
League universe is the moment before the biggest most satisfying sneeze and because its not a story game the lore is always gonna be on the verge of the sneeze. To be fair i love the game and the lore, but man i wanna sneeze.
I kinda don't want there to be a progressing story over the course of the game.
There needs to be a faction just for 
even though he's noxian.
I love how it's all these big factions and then just xerath. Like he is a big enough deal that he is just by himself.
