I think you either need movers and shakers; big names in that niche, to bring across a crowd of true believers, or just burrow in and be 'the guy' on steem.
When people start making their way across, they'll at least find you; and you'll always be known as 'the guy' who started the niche here.
My mate @dblstr is a lonely sneaker nut.
So he's put the flag out and keeps it flying in the breeze.