Could a champion that scales on AS and/or MS ever work?

I've been thinking about champion scalings lately (such is why don't more tanks scale off of tank items). After that I noticed something that never directly scaled for a champ, that being AS and MS. I know some champs have an advantage as they build those things, but we never see a here's a hard benefit for building AS and MS specifically.

People have been asking for a dancer champ since I started lol (probably before) yet riot has never done one. I'm assuming they've been kicking around ideas but it's a shame one's never come out. Could a feature like this be the sort of thing to build a dancer champ around, like a passive that turned AS into on hit damage and MS into armor and MR (rolling with blows better)? I mean we've got 2 wind champs, yasuo and janna, and neither scale on being fast. You'd think a wind champ would naturally want to build stuff related to speed.

Could we ever get a champ with a kit that directly rewards you for building speed related items?