Hivemind Communities will make following "accounts" less relevant as people will be able to follow interests instead. This interest-based following is much better than account-based following.
Let's say I write about Python programming, thoughts on Steem, life lessons and poetry. These are things that I care about and I would like to have conversations with other people who care about these too. Right now, all I can do is put it all on my blog account. There is no way to separate these different interests and no way to deliver each to its respective audience.
With communities, I can post all these in different communities and the right audience will interact with each. There will be communities for sharing poetry, life lessons, Python programming, etc.