13.5: Currently no path, because DTube accounts are still testnet accounts (and free, and easily to get multiple of) and it's just not technically possible yet. However we still already forbid people to use existing STEEM usernames on our signup.d.tube page (feel free to try it), this way the user is able to have matching usernames on STEEM and DTube if he registers on both.
Once live, we think we will onboard more people than our RCs will allow us to create, so if you want us to give free accounts to our users we can probably set up something linked with our curation process. (i.e. an avalon account receives a vote from our curation team but doesn't have a steem account? => we create it for him and encrypt+email him his keys). Such a system could already create a bunch of accounts, which would be 99.99% real new users because confirmed by our human curators through video.
13.7:
We have been managing our voting power and rarely hit 100% voting power through time, with 99.9% of the voting power being spent on dtube users videos. On the current STEEM value, that's about $500 per day, or $45K per quarter.
13.15:
Our project's vision is pretty clear, we are a video platform and want to get better at it. Everything on our roadmap is interchangeable and won't necessarily get made in the order currently listed or deliver on time (see whitepaper page 44). More unlisted features (like playlists, client-side encoding, self-hosting, etc) will probably get added too but it's hard to tell when. Tech moves fast, we have a lot of competition in decentralized video / media and need to adapt quickly, and to develop our software iteratively. So milestones are definitively not set in stone so and creating 1 year+ milestones would be more about imagination than rational planning based on facts.