Competition of the market is what guarantees the best for all of us.
I wouldn't say it's time to start powering down, and it'd be risky anyway, so it's understanable if you're not sure, whether you should take a look at Holochain.
But the whole thing is speculative. So far, I can't see any decline in Steem, it's not too late, and people won't start using an n+1 social media site if it's not established yet.
Steem is gaining a critical mass, though.
Anyways, only time will tell, but then again, competition is what'll tell who is the better. I trust in Steem but if any serious decline happens, I'll consider visiting Holochain, too.
It's up to the community, not only the quality.
RE: Steemit Has A Challenger