The upcoming WP-CLI release v2.0.0 that was originally due to be released on July 31st is being re-scheduled for Wednesday, August 8th.
This delay is due to the fact that it was much more work to disentangle the feature tests to split them up for the restructuring. I want to avoid hurrying the release, so I prefer to add some more time to let the dust settle and run further tests.
Thanks for your patience!