Has Diversity killed "Likemindedness" ?

I think the problem you're talking about starts earlier, on a personal level, rather than a social-level.

It's Individualism that has transferred into Isolation.

That makes people see diversity, that really isn't that diverse, but the lack of self-trust makes it seem dangerous, and an attack on your 'individualism' which it isn't, it's an attack on your 'isolation', and then it's really scary, because there's no fall-back from isolation.

If everybody is secure in their Individuality, diversity is a sampling plate, where you can figure out what YOU like, and you don't care if you agree, or not, because you can respect the individual in the other. The like-mindedness will be in the fact that everybody knows they're the master of their own fate.