The word μεθυσθῶσιν conveys the idea that "they might have drunk freely." Providing "good" wine (τὸν καλὸν οἶνον) toward the end of a wedding festival, lasting several days, is not what one would expect.
One's typical ability to determine "good" wine from average wine would be severely limited after freely drinking. That is because one's senses would be dulled in a process called palate fatigue. It would take a truly mind blowing wine, made with the depth and complexity of an orchestra of flavors to taste "good" in the middle of a wedding festival lasting for an entire week.
The magazine Wine Spectator describes palate fatigue in the following manner:
The term “palate fatigue” is typically used in large wine tasting
scenarios, in which, after tasting many different wines, they all
start to taste the same due to both the physical and mental exhaustion
of concentrating on how wine tastes. There are physical parts of
palate fatigue, including the consumption of alcohol, which is
absorbed in small amounts through the palate even if a taster is
spitting; the molecules of wine binding to the tongue’s sensory
papillae can also desensitize taste buds after extended tasting.
The other answer to this question involves determining the size of the wedding that took place, in conjunction with the four remaining days left for a typical wedding week of seven days to conclude. For a discussion of this specific question, see this post.
An analysis of how much wine was made, will yield an approximate total of 180 gallons. That's the modern equivalent of 900 bottles. Since the miracle took place on the third day, a total of four days would be left to consume the wine. If you do the math, it appears that rationing out all the miracle wine would yield the equivalent of just 225 bottles a day to be served.
If the whole village of Cana was invited, along with friends and family from a distance, the gathering could have easily been up to a 1,000 people. But even with half that number (e.g. 500 people), that's not enough for any one to get drunk. In reality it would only just be enough to have the equivalent of each adult having just a couple of glasses or so each evening during dinner. If any more wine was consumed, with that amount of people, they would have likely needed to acquire extra wine from other places - like going on a 2 hour walking trek down to Sepphoris.