Tighten has created a Collections only split from Laravel’s Illuminate Support package. This is designed for stand-alone PHP packages that would still like to use Laravel Collections. In the README it says it’s a manual split with the goal of eventually automating the process.
One issue report brings into question why it’s split under the Illuminate namespace and Matt Stauffer said this is done to keep your type hints consistent. To prevent conflicts Composer’s replace feature will be used so the original illuminate/support will be used if it’s required by any other package.
You can find out more on Github.