According to GoDaddy, you should maybe stop buying .tv domains because Tuvalu, who owns all such domain names, is currently sinking underwater. Once Tuvalu no longer exists as a nation, the domains will also disappear.
Sure, the island nation is slowly falling underwater, but all hope may not be lost yet. Valleywag points us to a USA Today article from 2004, which says there are exceptons—.su domains from the old Soviet Union are still active. But DomainNameWire refutes this, mentioning that factoid came from a VeriSign, a company that handles all domain transactions for Tuvalu, and their reasoning might be skewed. They instead reference an ICANN rule which states that domain names from any defunct country must be phased out.
So who knows what will actually happen when Tuvalu decides to swim with the fishes. But seeing that .tv domains have big time marketing appeal, I'd have trouble believing they'd just nix the domains. Still, I'm no internet domain lawyer—domain squatters, you might want to heed this warning: BEWARE OF SINKING ISLAND. [Wreck and Salvage via Eddie Codel via Boing Boing and DomainNameWire]