As I see it there are two options for competitors:

1. If Steemit grows large at a rapid rate in this niche and becomes big enough, competitors would be interested in buying it up to gain all the followers and impement it in their own system.

2. If Steemit grows at a slower rate and just shows a good potential but does not take of,f the competitors might as well just copy the idea in their own system. which is very likely just think about all those likes in FB being converted to crypto currency.

Currently using Steemit for a book project check it out in my blog:
Millionaire Shortcuts: Money should just be a byproduct of your goals in life