Over the years, US carriers (yes, always in carrier groups) have repeatedly been sunk by subs. Usually diesels. British, French, Canadian, Dutch, Swedish, Australian.. even Chilean subs have all taken turns sending the pride and glory of the US fleet to the bottom in wargames. From the 80s, right through to 2015 is the latest example I can find (a 30 year old French nuclear sub, that time).
IMO The Aircraft Carrier in 2020 will be what the Battleship was in 1940. Sub-launched cruise missiles allow for sudden deep strikes, drones can operate from much smaller amphibious assault craft, which can follow up to land the required ground forces to go along with an operation, not just be a floating airport. Smaller UAVs can be operated individually by battlefield units, larger ones from FOBs and semi-prepared advance airfields. Air defence can be provided by ground units, recon & ELINT by UAVs & satellites, strike missions by UAVs & cruise missiles. Navy doesn't do strategic bombing, and naval CAS is generally done by Marines off amphib ships, with rotary and V/STOL (Harriers & F-35B).
I really can't think of anything that a carrier can do and will be doing in the near future that can't be done by something else, and that justifies the price tag.
Though yes, they're still cool as fuck.