Since its introduction, Arrow has remained fairly grounded and realistic. In so far as a show about a bow-weilding vigilante can be considered realistic. But since introducing the concept of meta-humans into the show, things have changed dramatically. Vixen's ability to channel the strengths and abilities of various animals isn't too flashy, and keeps her on the low-end of the power spectrum in relation to characters like Superman and Wonder Woman. Because of this, the character could fit well into the show as we know it. Most importantly, Vixen has already been confirmed for a CW animated series set in the same world as Arrow and The Flash. As both heroes are confirmed to appear in the animated show, it wouldn't be that surprising if Vixen returned the favour. Once Upon A Time has already shown that characters can successfully make the leap from animated to live-action quite successfully, so why not have Vixen appear in the next Season of Arrow?