I really Like the idea. But cutting off the hammers in the kingdom zone hamper too much (adding one boost too much).
I foresee a capital with just 6HP/zone but three loyalty symbols for each Faction...(this would give a chance to legends !!!)
An Order or Destruction capital with a symbol of each allied factions but with 6HP/zone.
A Lizardmen capital that reduce the cost of the first lizardmen unit you play each turn by one but have no loyalty symbol.
An Undead one on on which you have to dump the first card of you deck in the discard at each of you quest phase but no loyalty symbol.
A Skaven one that boost +1 dmg for each of you attacking units but without loyalty symbol.
A Wood elf one that begins the game with a developpement in each zone but no loyalty symbol.
A bretonnian one that reduce the quest cost to 0 but without loyalty symbol. (but there are not much bretonnians yet).
I think Fantasy flight should check the possibility of creating officials (balanced) one (and accept them for tournament). That would expand the possibilities.
Its sad I'm not a talented ''photoshopper'' . I'd create those myself and share them to the community. I wonder if a good fellow would do it for us !!!???