The requested package drupal/datetime could not be found in any version

Commit #cb0ad00 removed drupal/calendar_datetime in favor of drupal/datetime (Nov 26 2016).

However, now drupal/datetime is coming back as "no matching package found", and I'm not quite sure what it's referring to -- perhaps the datetime module that is in core?

It could be a temporary packagist issue (since I've installed this module via composer since Nov 26 just fine).

I am are having a related problem, not sure if it is the same. We can not get the module to install via composer, we keep getting the following set of errors when running "composer require drupal/calendar:1.x-dev"

./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.
  Problem 1
    - Installation request for drupal/calendar 1.x-dev -> satisfiable by drupal/calendar[1.x-dev].
    - drupal/calendar 1.x-dev requires drupal/calendar_datetime * -> satisfiable by drupal/calendar_datetime[dev-1.x, 1.x-dev] but these conflict with your requirements or minimum-stability.
Installation failed, reverting ./composer.json to its original content.

@StuddMan
Did you ever find a resolution to this issue? I'm preparing a make file and keep hitting this issue with calendar_datetime.

This is a dev version for Drupal 8. Make sure you check your composer.json file to insure the minimum stability allowed is set for dev versions of modules. If this flag is set to alpha or higher it will cause a conflict. This is ok in development environments.
"minimum-stability": "dev"

You can also mark a single module's stability. (This did not help with the include of the calendar_datetime dependency conflict)
{
"require": {
"drupal/calendar": "@dev"
},
}