Anything that’s not already in Helix should not be expected to be in Helix when v5 is shutdown.
If you want things added you’ll have to submit a feature request on UserVoice https://twitch.uservoice.com/forums/310213-developers or vote for existing ones for those suggestions.
It’s also worth being aware of the Migration documentation as some things such as all of the Collections endpoints have already been marked No longer supported via the API.