Thanks a lot @chrismccord. I know you have burnt a few midnight candles to keep my word. (You did burn the candles. For keeping my word is the joke. )
phoenix_live_view/CHANGELOG.md at master · phoenixframework/phoenix_live_view (github.com) LiveView 0.18 is released. I am sure Phoenix 1.7 is round the corner.
It is a major release and I am eagerly waiting for it.

For some guidance, there is also https://www.phoenixdiff.org/ which shows a diff between the output of phx.new run against different versions. It’s not exactly an upgrade guide, but it can help spot changes between versions.

AFAIK you can run it locally too, which is probably required to diff a pre-release version.

Generally, the practice with Phoenix is It gets released when it is ready. Working against deadlines is not the opensource philosophy - and - @josevalim and @chrismccord embrace that fully.
Having said that, the pace at which the commits are being done in both phoenix and liveview - add to that the if you create a new app with the present master branch it creates a broken application - I am reasonably confident that we are <2 weeks for the release of both. Because of the many breaking changes that that are there - I have a feeling that both will be released simultaneously or very close together. LiveView 0.18 first and then Phoenix 1.7.
Though the above is my estimate - @cblavier might be privy to more information - because soon his work storybook will be absorbed in core. So if he says a few weeks - it is few weeks.
Further as @cblavier suggested - never good to plan a project on a hypothetical release date.