The splash artists at Riot decided that they will update all the older, Classic splashes, and only when they finish with classic splash they will get to skin splashes.
Also, splash updates don't necessarily mean an ingame/model update. The new classic splashes that come without any Visual Update of some sorts, are meant to reflect how Riot would have done the Classic design of the old champions these days, I think, while keeping the old design and still making it look very similar to the old in game model.
So Jarvan's splash wasn't updated with a model or anything, but it wasn't really changed so drastically, and the only major difference I can spot is the face (and the colors are just a matter of lighting, so that's not really anything new).
Also, splashes (Even for new skins and champs) are meant to reflect the in game model with extra details (This can be seen in splashes like how the new Headhunter Akali has a lot more details in her rope-belt-thingy in the splash, while in game it doesn't look as detailed, and with someone like Urgot who had his splash updated but now has a different skull on his shoulder-piece, his mask-helmet has 4 holes instead of the in game model's 5, and he doesn't have nipples, lol).
And about Dragon Slayer Jarvan, he will have an updated model with his Visual Update, whenever that would be, and as I already said, his Dragon Slayer splash art will be updated after Riot finish updating all the old classic splashes and Jarvan's in game models.
[{quoted}](name=the Salvation,realm=NA,application-id=A8FQeEA8,discussion-id=KLFj57e6,comment-id=0001,timestamp=2015-03-24T08:41:14.742+0000)
U STUPID SHIT DIDNT SEE DIFFERENCE. MORON WHERE IS YOUR INTELEGENCE. ITS EXACTLY DIFFERENT ON FACE, HAIR, and ARMOR
And BTW, you don't have to rage so much on Dragonzilla's comment only because he said he didn't notice much difference. :)
(Sorry if I made my point too many times, I'm in a hurry and I don't have time to go over my comment again)