I'd put myself in the "optimistic" camp, but not insanely so (like some on Steem).

The blockchain itself is sound (high use, very fast & free transactions), and Steem has first-mover advantage in the social space, with a fairly decent sized, active community.

But I don't think it will break out into mainstream adoption until the development team realise they need to get serious UX & marketing help to drive it forward as a business, rather than a tech project.

The communities features will help (when they arrive), but Steemit needs a lot of work & constant A/B testing, if that's where they're hoping to drive adoption.

Where I hold out the most hope is with SMTs, and there being a (possibly multiple) killer app using the Steem blockchain and that affecting the price of Steem and bringing more attention to the rest of the network.

Appics looks really promising, but I'd love to see more original dapps coming, not just blockchain versions of already established platforms (like Steemit vs Reddit, DTube vs YouTube, Appics vs Instagram).

So yes, I do think Steem has the potential to reach the top 10, but not yet. I'll keep on keeping on and my fingers will stay crossed.