Some of us talked a little bit about this when we met in Basel. The interchange protocol was added to pandas a while ago, but we believe that it would be beneficial to remove it from the pandas main repo into a separate repository.

The main issue is that bugfixes to the interchange protocol are currently tied to the pandas release cycle, which means that users might have to pin the pandas version if they run into a bug that they care about. Having it as a dependency decouples the releases, which can make the protocol much more responsive and pins are no longer tied to the main pandas repository if necessary at all.

The package would be a pure and lightweight Python dependency which makes it easier to contribute for others, because the testsuite is not slowed down by the pandas testsuite.

The new optional dependency is extremly lightweight, no additional dependencies brought in and only around 30kb in size, so it really doesn't matter much.

Those are really small downsides for improved interoperability and the decoupling of release cycles for both components.

cc @pandas-dev/pandas-core