Curation shouldn't be part of the 1st layer. The current form of curation is a failed system btw IMO. You can see it by the voting activity of bid-bots such as appreciator & upmewhale. They're upvoting new content to maximize their rewards, regardless if it's trash. Other content, which would deserve higher rewards, they're not voting as it would reduce their own rewards.
RE: Can Hive scale under its current reward distribution mechanism to millions of users?