Yorick would have those dirty teared clothes with the old lamp on his back, his very common-looking shovel. His skin would be green, as if he was decaying. The ghouls could look like the original ones, and they could come up with something for the maiden, maybe making her the same colour as his old ultimate ghost.
About Warwick, the main difference is their accessories. The new one has mostly chemtech empowering systems, making him look like Bane from DC universe: a character whose sole power comes from chemicals. Old Warwick looked much more feral, more wild. Instead of pumping himself with technology, he chose simple armor/weapons, embracing his new features, despite being able to have the same things as the current one.
I totally disagree with the statement that their traditional skins would be chromas, mostly because you think that they would have the same features: "WW would still have his arm and those pods on his back and Yorick will still have his cape". Those are key features to the new version, not the old one.
Traditional Karma for example, is the only Karma skin without the weird cape behind the dress kind of thing. Her main differences are the dress, her hairstyle and the fans (that appear only when she dances....). Heck, Traditional Sejuani is just half-naked Sejuani riding more of a pig than boar. Is it that different from the normal one?
The thing is, every small detail matters. When Fiora was changed, people immediately wanted her "hair" back. Just one small patch over an eye. Traditional Skins by themselves show the initial concept of the champion, which has been changed from, based on either storyline (Trundle) or appearance (Sejuani, Karma).
