I think there are many interesting ways to record and organize data which don’t fit into GEDCOM. Saving a set of objects is less of a problem than representing it to users, so they can understand them and benefit from the changes. Clans/tribes might be possible just as a list, but how would you present heterogeneous sets with complex relationships where a list is not sufficient.
One idea I had recently was creating organisation objects:
Families record close individuals through biological (and non-biological) relationships (e.g. parent-child), associations do that for friends and acquaintances and organisations would connect unrelated individuals through their jobs/positions in an organisation.
Person events especially occupation and military should take places as well as positions. The organisation should be a (hierarchal) list of job positions. Each position would be a list of individuals and a date or a time range when they had this position.