Title needs to be changed to "how long does a bottle of wine keep after it is opened", because I can assure you from long experience the answer to the titular question is: about an hour and a half.
They do make cans of wine... I know it's a crazy idea, but my friend who likes wine loves the single serving size.
For a joke, my family got me a 750ml glass a couple of Christmases ago. I have yet to use it.
I can drink a bottle myself lunch to bed on a weekend, but not every weekend.
Pretty sure that isn't the only brand I have seen.
A bottle is obviously better long term.