It's coming, apparently. Just no date set. Since they seem to be pushing everyone in that direction, I would assume it will be available some time this year. We are currently looking at selling a private key at this point, and I think that Roku seems to be trying to figure out how to prevent that. I'm fine with it - they have to make money - but the feature should be coming sooner. It's been almost a year since they launched Direct Publisher - time to monetize it.
"Currently, Direct Publisher only supports ad monetization. SVOD and TVOD are not yet available."