Yes, the I-400
http://en.wikipedia.org/wiki/I-400_class_submarineMissile armed subs (like those Tomahawk-armed Ohios) will probably replace carriers as the 'capital ship' sometime in the future (likely after the USN loses one of theirs in a conflict), for a variety of reasons.
1. Subs are far harder to find than carriers.
2. Cruise missiles these days are incredibly accurate and can do the same job as a fighter-bomber most of the time.
3. Subs are cheaper and far more cost-effective.
4. If you lose a sub, you lose 100 sailors or so. If you lose a carrier, you lose 5,000. Even more if part of the (or whole) task force goes down with it (after a nuke hits) That's a helluva lot of letters to write...
The only real advantage a carrier has over a sub is it intimidation factor.
The USN has tried to maintain a strong capability in both carriers and subs, but as time goes on (and prices increase), it fields fewer and fewer of each type of vessel. Eventually, it will get to the point that it can't afford 12 carrier task forces.