I like the League of Legends lore. But i feel that with every new champion Riot is just adding more and more storylines to build on.
The thing about stories is that...they end. They have a climax. Where is all this build up going? This is a really pessimistic thing to say but League of Legends simply can't live forever. Let's say this game pulls on a TF2 and is still going relatively strong in 10 years. Will we still not have any satisfying conclusion to some of these story lines? Sometimes I worry that this game will die with all of these lines not coming anywhere near an end.
Don't be afraid to tie up some of these story lines. You can make new arcs. Like, it seems like in the lore the Void or Darking or whatever gets closer and closer and closer, but it never arrives. But it's right around the corner! Any day now! Aaannny minute.... Closer and closer...