In our HubSpot Portal we heavily depend on and utilize lists, especially active lists for email campaigns and workflows. Due to this we frequently run into the issue of running against the list limit. A feature that I would find useful to help with this problem is the ability to export an active list filter set and have the ability to import/recreate the same active list at a later time. Note that this does not need to export contacts/deals/companies within a list but rather just the filter sets applied to the list. It would be best to also include other list details like name and description.
This use case would be most useful for lists utilized for campaigns that only reoccur annually or quarterly. Once the campaign or use case is done, users do not want to delete lists in that they will have to recreate the filter set again (which at times can be complex and time intensive to set up as well as hard to remember exactly how it was set up before).
As a quasi solution we can screenshot the filters to refer to later, but it still requires the lift to building again.