Playbooks are ostensibly about niche protection, right? Only one gunlugger in the game, so no one else steps on her toes, ditto for the hocus and the operator, etc.
If you want to introduce modularity, I think you could make it work if you had two independent dimensions of niche you wanted to protect.
D&D 4e might offer an interesting example. It had at least two mini-games, offering two dimensions of niche: the combat mini-game, and the skills mini-game. The classes were categorized by their combat niche, which was called its role: striker, defender, leader, controller. Each class had a specific take on its role, and that's a cool part of the game. But the skills also form clusters that offer niches, too: every party wants a face, an athlete, a burglar, a nature dude, and a lore dude.
The 4e solution to this problem, was a complex system of classes, each of which combined a primary combat role, a 2ary combat role, and an area of expertise in their class skill selection. These niches were loosely correlated with role (eg. strikers are often burglars, defenders are often athletic types, etc.), and loosely correlated with power source (arcane dudes tend to make good faces or good lore masters, primal types are often good nature dudes, etc.).
But another solution would have been, of course, to make the two dimensions of niche completely independent. That seems to be the direction they're talking about for D&D Next. So, if you want a tank who can sneak and disarm traps, you just pick a tank class to set one dial, and pick thiefy theme and background to set the other dial. In AW terms, you'd want each playbook to offer moves that pertain to different aspects of the game, only loosely connected to one another.
In a Werewolf game, I'd look at each splat-category (especially tribe and auspice, probably not breed), and figure out: which aspect of the game is this supposed to influence the most? Auspice is essentially a werewolf's caste in Lupine society. So, I would expect my choice of Auspice to determine how I advance politically, perhaps by providing moves that let me increase Renown in given circumstances appropriate for my Auspice.
Tribe, on the other hand, has a lot to do with the relationship to the spirit world via a specific totem, and by implication, the werewolf's relationship to human society and to nature. So I would think that would give each tribe a certain domain in which they could be masters, eg. Glass Walkers in the middle and upper classes of human society, Black Furies among women and the oppressed, Fianna among romantics and artists, etc.
(Breed doesn't really fit this pattern, but I don't think you'd want a playbook approach to breed anyway. You wouldn't want only one homid, only one lupus, or only one metis in the game, right? So breed is probably a tertiary option that you can add to any other auspice + tribe combination.)
Does this help? Is this the sort of thing you're thinking about?