I'm really hoping for Karthus to finally get his splashes updated, they barely serve justice to his actual skins (Phantom, Statue, and Reaper).
I don't really remember anyone else on the splash update schedule except Annie I think, but like I said, who's next on the list?
Swain and Irelia will probably get new splashes with their reworks
was mentioned as a likely candidate, but hoping its somebody else.
Well I've read they will likely avoid doing 2 female marksmen back to back(so no Sivir or Ashe,though I feel like Sivir should be a high priority).
I'd say that 
and 
would make the most sense to me.
Alistar has a skin that you can get for free,so his skin is the first skin for many players,so it should at least look good(this was also a reason why Tristana got her skin splash arts so early).
And Karthus has probably the biggest disconnect between his skins and their ingame models. I mean seriously,statue of Karthus and grim reaper look nothing like their ingame counterparts.
