While a pack of 1 HD vampires taking on Village of Hommlet may fire some of my synapses, I keep thinking back to Sabbat characters as the ultimate murderhobos (remember to skip the last 10 minutes when you re-watch "Near Dark") even without adopting the cult/organization membership as the binding mechanism for party coherence. It's too tight conceptually to work outside of specific campaigns, though I suppose the Cleric of Khorne might be able to create potions of healing by mixing the blood of all the party members. I still feel there's something there in the mechanics even if the trappings don't work, especially in a party where a handful of PCs work with a larger number of henchmen and hirelings. The vaulderie takes place in the form of sharing treasure, shaping the loyalty of the hirelings to the party and the willingness to take risks, or simply keep working for a boss they dislike. Not much better than the typical Charisma-based loyalty rules right now, but the concept will remain percolating in my brain while I obsess on how to apply it.
My other hireling and party interaction fascination is the old Warhammer Realms of Chaos books, specifically the warband concept. For the unfamiliar, it's an (ideally) narrative wargame campaign, where each play creates a fledgling champion of one of the Chaos Gods and puts together a ragtag random entourage of monsters and followers. As games are played, the champion gains abilities or mutations based on their success (calculated with bias to the God followed), eventually becoming a daemon prince sitting by the right side of their god (winning) or a barely sentient ball of tentacles and mouths.
One aspect of old-skool D&D that I haven't seen successfully improved by the OSR is handling followers during exploration and combat. Sure a couple of hirelings, especially when PCs are at low levels, but once higher levels are tracking a menagerie of ablative targets becomes both less useful and a pain to manage. There are some great resources likes Meatshields and Hireling traits generator for creating them, but once combat occurs their utility fades along with their chances of hurting Ogres and the implementation of magic light sources increases.
We can learn from wargames on how to handle the large numbers and use of some abstract benefits, which plan to get to in Part II and explore in details in my Supplement C.