> Why, and more importantly how would it lose its ethanol content?

Most wine bottles lose their ethanol within decades because oxygen makes it through the seal and the ethanol evaporates or reacts into something else. Any wine bottle that survives to hundreds of years old, even perfectly sealed, will have bacteria converting ethanol to acetaldehyde and acetic acid via aerobic and anaerobic pathways. 200-300 years is normally the limit before wine loses all ethanol even without a leak.

Which bring to mind those bottles of Napoleon era champagne found preserved under pressure in a ship wreck. Any info on how those turned out or was the one opened a palatable vinegar?

Perhaps with a dash of cobalt-60 we can ensure both a long shelf-life and discourage premature opening.

Sorry, your comment is bullshit.

>Most wine bottles lose their ethanol within decades

Not true at all, even for bottles sealed with cheap, short corks, or bottles that leak. One delicious example is 1977 Vintage Port, which is notorious for faulty corks. Roughly speaking, 1/3 to 1/2 of corks failed even with good storage. And yet - the port inside is still in near-perfect shape, alcohol intact. Indeed, I just opened another bottle of '77 Dow's the night before last, and it was flawless.

>200-300 years is normally the limit before wine loses all ethanol even without a leak.

Also entirely untrue - I have wine in that age range as well :) And once again, some of it has leaked, and once again, the alcohol remained intact...

If you don't believe me, I recommend looking up tasting notes for old wines. There are plenty of datapoints on this particular subject. Or, you could buy a bottle! Vintage Port with fifty years on it isn't terribly expensive for the quality and age of wine you're buying.