helhum/typo3-console is not an extension any more, but a regular composer binary, which will be pulled into your vendor folder in composer based TYPO3 projects. Not required files will then no longer be delivered, when fetching the composer package as distribution and not by source.

The git repository itself still contains all TYPO3 extension files, so cloning will work until the next major version release. It is however not recommended to do so.

If you need the console as extension in non composer based projects, then download and install it from TER, by using the TYPO3 extension manager.

Deprecations

Cloning the repository as way to install it has been deprecated. The extension files will be removed with the next major release.
Installing and using the typo3cms binary from the project root is now deprecated. It is recommended to use the composer installed binary instead. Custom installation code will be removed with the next major version.

Bugfixes

Flush correct cache directory when doing cache:flush --force with TYPO3 8.x
Make frontend:request work again with TYPO3 8.x

Full list of changes. TER release page