Is a world primarily focused on intrigue and politics widely sustainable?

[Sparky McDibben]

Well... there’s a single human nation with a government-in-exile off continent and a single on-continent city-state which is basically ignoring the original government. There’s also a ton of denominations of only three pantheons, as well a bunch of secret organizations like a necro-army and such. But I’ll keep that in mind, I definitely think I need a lot more factions for my elven democracy.

So I'm seeing only a few organized nations from your description, which I'm also seeing as a lot of blank space to explore. The great point here is that you can apply that to both types of players along the political-to-murderhobo spectrum. Murderhobos just need a patron to point them at a dungeon. Politically savvy players will enjoy having multiple patrons with conflicting goals, all of which can collide either in the wilderness or in a civilized setting, so it's more a question of how you present the hooks.

The orcs here are actually refugees pushed out by Goliath invaders, so they’re seen as savage invaders by the “civilized” races. I’ve never really liked the concept of bandit gangs in high fantasy though, seemed so anachronistic.

I guess I'm a little confused by this. How would you say bandit gangs are anachronistic? I would say that bandits arise from a breakdown of central authority. Central authority can be either present or absent in high fantasy, so I'd argue bandits are perfectly viable. However, if you're thinking that bandit gangs couldn't compete with powerful mages, then the solution is simple: the bandit gangs are run by magi. Maybe some of these gangs are run by mage-school dropouts, little better than sadistic thugs with heat metal and a rod. But maybe some bandit gangs are actually run by a mage patron who handles arcane countermeasures (casting nondetection or supplying the bandits with amulets of proof against detection and location for example). What if a powerful mage has several bandit gangs on the payroll, and each of them have contingent spells set up so that if the bandits try to rat them out under interrogation, the bandits suffer some horrible fate (fireball? dominate person? brain melting? Knock yourself out!). There's a lot you can do there.

It’s Halfling, but they stopped after they bombed their magical metropolis by accident and now it’s the headquarters of the undead army.

Hells yeah, brother!

Mostly what I wanted to do was enhance stereotypes, by giving them reason to exist in the world like in the default setting but also subverting it.

Yeah, I'd definitely recommend Eberron as inspiration, then. Sounds like exactly what you're going for.

I play 3.5e, so don’t really know about that. I... guess that could work?

Disregard this point; it doesn't apply to 3.5. I remember the Dark Times.