I've heard the Samnites described as proto-communists, which I think is a loathesome descriptor - But everything I've read suggests that it was more communal than individual, so more trading between entire tribes, rather than between individuals.
It does suggest a more collectivist approach to things.
It could be interesting if they could be united under a form of representative quorum, lead by a "Consul","General","Warleader", I'm going to stick with Consul. The Consul has basically free reign in external matters, and some in internal matters - but there is a balance between his powers, and the powers the tribes have over their territories.
Plus, it means that with new conquests - new groups can be invited into the quorum, even in entirely artificial. Conquer Neapolis? The 'Neapol' are invited, despite being lead by a Pro-Samnite leader that they've chosen.
Does this eventually get too large to control? Probably - but this is why tiering works!
I'm thinking a combination of the Hellenic League for the military and diplomatic powers of the consul, but without the voting relying on the military BUT the requirement to provide military forces equivalent to X% of manpower, men, money, etc.
Fundamentally, you need someone to come along, and resolve any conflicts between the main Samnite groups, and establish common laws and defined areas of influence for each group.
For the world? No "Roman Empire" - Depending on how this military federation works? Potentially a militarily cohesive, if culturally diverse Italy.
I'm curious as to how the identity politics would work, whether groups would start assimilating with each other, or subdividing - and at which point should a group be added to the quorum?