You have to remember that arcade riven was a fan concept skin which is now being made so anything is possible if you get a big enough support behind this skin but you also have to think what kind of skin will it be a 975 RP skin, a 1350 RP skin, maybe even a 1820 skin, or if you can come up with a cool way for riven to have a unique function like DJ Sona or Spirit Guard Udyr then maybe a 3250 RP skin but if it does become a 3250 skin then it would not come out until another 2 years from now around or so. But i think it is sort of contrary to how Riven is she would not want enhancements that would be a waste of her sword being broken as she wants to redeem herself for what she has done and does not want being part machine to come in the way of that. Because then she can be controlled and she may lose her mind like Viktor and undo all the good she has done to redeem herself of her past sins.