I wish I knew which threats to the system

The system generalized, not just the Steem environment.

Yet somehow I still find more good content each day than I have time to read.

I agree but it depends on how one approaches content and people. Most value what they think will give them immediate advantage, it is cutting content corners and then they wonder why they do not enjoy what they consume.

And still find such meaningful comments on most of my posts (though one dear to me seemed to get skipped over by everyone the other day).

Annoying isn't it? DM me a link :)

We are going to be helping these teens become better readers and better writers, using Steemit to do it.

I tihnk that in time, there is going to be a n increasing branch of education on Steem to the point where there will be specialized dapps for it. It is likely going to be one of the most successful/influential components of the blockchain as it can bring a vast amount of organised and trusted material to many people cheaply.

Good luck :)