Iggy had a cosign from tip, miley had juicy j and 2 chains ft tracks, none of them are new niggas. Post is a good example that rap has hit the mainstream, he didn't need the cosign to get hot, white kids are listening to it and he can eat off those numbers alone.
I think we've hit peak rap anyway, trap is basically a meaningless subgenre at this point. Anything with spacey ethereal sounding keys and hi hats and a mention of drugs is considered trap now. Everybody is trying to capitalize on the sound, it's basically the new hair metal.