When talking about the issue of account retention, never forget that a good portion of account creation goes to bots, which are either designed to never post and only vote (for money) or never vote and only post (content formed off the web or generated by Markov chain).
It's probably impossible to determine if any given account is a bot or not without specifically looking at their pattern of engagement, but we know they exist and they exist in numbers.
in massive numbers.....
If I was prone to scatological communication, and I am, I would say "in pant-shittingly massive numbers, far beyond the numbers of mortal ken."
But we can't know that for sure. We can just look at the behavior of these accounts and wonder.
Though it is a little comforting to think that at least most of the accounts which were created and have done nothing since might have been for bots that the author has forgotten about, which is good.
I have a very fuzzy prediction which I would be happy to discover was wrong, that the more activity around SMT and the upcoming hardfork in terms of PR and social push, the more accounts that we're going to see getting pushed to be created with the Steemit-delegated SP, purely to act as batteries to be used for something in the future, after the fork.
I would love to be proven wrong, but we'll see if reality catches up to me.