Ghost was a good idea but seems to be dead. Last post I can find is from last year. It's design inspired my own service however which was a nice silver lining.
You may just have something different and great with the "private writing." Seriously does anyone care 1 million people read them, or a select 100, maybe even a select 10 then you can have a meaningful discussion with those. Private writing sounds more innovative to me then Medium, Sbvtle, and the likes.