I started thinking about this a bit too, here. I'm particularly interested in the idea that governments may have access to otherwise-undiscovered anti-crypto techniques, which while they couldn't employ them against a network overtly, may be useful in certain directed attacks, e.g. Large transactions, specific IPs or addresses etc.

More likely, there's a possibility of targeting machines through trojans and other network attacks - recent South Korean events point at this, for instance. You wouldn't need to attack the network itself, but a coordinated attack against a particular pool, or country, might be effective enough to allow a different attack, or disrupt btc going into a region at a crucial moment.

But I suspect we'll see a few states doing dumb stuff like insisting all wallets have to be "declared for tax purposes" (and tracking) first. If they're not doing that covertly already.