Middle class isn't exactly a well-defined term in any field. Some focus on being above poverty, some define it in terms of middle incomes/wealth, or not having to work with your hands, some just say it isn't the poor or the rich, but those inbetween who do well, well enough to have something to spend beyond the necessities of life.
I think a middle class on Steemit should be wealthy enough to make eachother wealthier at a fair pace, even in the face of the huge amounts of Steem being in a few hands, and passive, and 35% being behind bid-bots, and so on.
As wealth is a relative thing, I don't think we will ever see such a middle class on Steemit when it is up against what Steemit and the Steem distribution has evolved into, and I see no way at all of doing it just by producing content, which is what I came for. Also, I doubt a middle class will ever emerge that is supportive of eachother, as opposed to people soloing about with short-term goals and picking whatever path they see to increase their individual wealth as fast as they can without looking any further than that.
Anyway, middle classes tend to disappear in some incarnations of capitalism, and I think Steem/Steemit is one of those incarnations, as in its current state and set-up, it over-emphasises making money with money, which leads to concentration of wealth.
I hope I'm wrong, or will be at some point.