THEORY TIME:
Riven and Yas are known to be the toxic king and queen of the Rift. With the new Riot Pls video out today it was mentioned that your honor level has real rewards that include exclusive content.
I think that Riot is going to slightly troll by making ABRiven and DBYas only obtainable through high honor play. Just a guess...
Thoughts?
Probably not. There "symbols" seemed to be attached to the new missions system. So if anything theyll probably be attached to that.
I really hope not. I have been waiting for Angel Blade Riven for a hot minute. It would be an interesting concept, but I'm really hoping not. 
So Angelblade Riven is only available to honorable players, while Demonblade Yasuo is available to toxic players? Sounds legit :P
In all seriousness, I doubt it. The mission assets that were added to the PBE (as mentioned by FallenReaper88) hint at DBYas and ABRiven being regular skins that are possibly obtainable through missions. Would be nice if they were exclusive content though...
I highly doubt it. Riven and Yasuo skins would net riot huge amounts of cash relative to other champs. Seems like it would be missing out on a big opportunity.
Maybe, I would love it to be that way, cuz thats hilarious, but I Think thouse skins are coming out befor the new honor system. I'm not sure though.
It won't, these skins release in 7.12 while the honor system's earliest release date is 7.13
