Nah, tank nidalee and katarina won't be meta ever. Unless some new balance changes come out.
Akali works because she just gets insta nuked pre-6, building tank lets her stay alive so she can deal her damage to begin with. Her entire kit revolves around diving people, so it kinda makes sense in a way. Nidalee can just chunk you at a distance and you wouldn't really get that with tank.
I think you are confusing strong with viable. Just because Akali can do good doesn't make her a new meta. I play it and I like it, but I play it because its finally a viable Akali build, and I have a ladyboner for Akali, not because I think shes statistically top tier