The carriers are not hard to sink; they never really have been for a major opponent. China and Russia have been able to sink them for a long time. They're not for fighting adversaries that can sink them. They're force projection, intimidation, and for fighting countries that aren't Russia or China. Carriers will be useful in their present role for a few decades to come yet (their current role is not for potentially fighting Russia or China; anyone that thinks that is seriously confused). Military tier nations in the capability realm of Iran, might pose a real threat to carriers in 15-20 years. The trick with US carriers, is that anyone (again, not named Russia or China) that actually sinks one has a full scale war with the US on their hands. In that sense, carriers are a taunting device: you can try to sink one, but if you succeed, your country is going to be massively attacked (you're going to trade sinking a carrier for losing all your airports, your power grid is going to be taken down, your airforce is going to be neutralized, your economy is going to grind to a halt, etc).