Are we seriously talking about Grodd as a possibility? Flash
is being spun off from the initially realistic and grounded Arrow
universe. They're expanding into technologically-induced superpowers now to accommodate the Flash
spinoff, but I doubt they'll go too far into fantasy.
Although I wouldn't totally rule out a story about, say, someone genetically engineering a superintelligent gorilla who turns out to be malevolent -- but who speaks in sign language rather than English. In fact, I could've sworn I'd already seen that done on an episode of Lois and Clark
or something, but Wikipedia doesn't mention it.