Probable exceptions: 
Confirmed exceptions: 
Bonus points if it is the lore team answering
More bonus points if they can correlate the answer with alternative universes
as well as are other possible exceptions.
Oh, I know! I know what they have in common. They are all featured in this OP.
I win.
They all take notice to the summoner...?
I think it's something family related, but since doesn't have a family, not even a dead one, he ruins every theory I come up with.
Edit: Well I was wrong.
For who didn't guess it, they are the champions that have yet to receive a lore update in years
Exceptions are Kayle and Morgana (champion update) and Yordles (Bandle City future update, though they are potential since they may not touch all of them)
But apparentely Riot lore team cares more about alternative universe's cash cows instead of actually putting everyone on the same level before updating the general lore
(EDIT) you may think got one, but we literally have yet to get anything meaningful, proof being they haven't yet given her a proper backstory and all we have is her hunting session
I'm assuming the Demacia event with Sylas' release will lead into the Kayle & Morgana update and round out the Demacian champs.
Demacia:
It was said that the Freljord bios would be updated at the end of Ashe: WARMOTHER's run.
Freljord:
As you stated, we may receive the Yordle update this year. However, I think there is a possibility Rumble and Corki are moved to Piltover and updated with Heimerdinger as Piltover champs. Similarly Ziggs might be updated whenever they return to Zaun.
Bandle City:
Void lore may come whenever Cho'gath or Kog'maw receive a rework, or they may surprise us with it this year. Noxus and Zaun will likely be returned to in the future.
Void:
I'm betting that Alistar's lore will remain focused on his enslavement in Noxus, and not with him being free just yet.
Noxus:
Zaun:
These are the ones you need to worry about, see all the others can be placed into a category and potentially updated, these few we're not sure when they will be updated. If I had to say, Bard being a celestial may see an update whenever we return to Targon, and Jax and Zilean, may be updated as Icathian's whenever they do the Void lore.
Runeterra:
