My idea specifically focuses on the vending machine. If a vending machine could have a water hookup, then no water would need to be delivered to the machine, only the other ingredients and packaging: CO2, sugar, flavor, and containers. Water would be filtered and carbonated on the premise. I envision a partially clear machine with an LED light show to accompany the on-the-spot production of your beverage. And the system should never be out of your favorite beverage, since the machine's inventory isn't tied up with storing a lot of water, and it has a surplus of the other ingredients. It could even make you a drink with "extra fizz" if you wanted.
For the bottles, I imagine a lighter-weight bottle, perhaps something collapsible, that would make transporting them easier. Or, if possible, the machine could injection-mold the bottles on the spot as part of the show (like the machines at the Henry Ford Museum that create plastic Henry Ford figures or Oscar Mayer Weinermobiles while-you-wait). A vertically-integrated vending machine!
This would allow for the best possible part of this idea: the people who service the machines. I've often thought it a shame that there are no more paperboys. The youthful paper carrier with a 50-customer route is gone, replaced by adults with cars that deliver several times that many papers. This is a great loss for kids. But if the various components needed by the machines were lightweight and compact, they could be delivered by a 14-year-old with a bike. The machine could even send text messages to the kid to let him or her know what supplies are running low.
The idea has problems, of course. There are far more electrical outlets than there are water lines in prime vending locations. People might trust their newspaper to be delivered by a 14-year-old, less so their beverages. I don't know if the collapsible bottles I envision could stand up to the carbonation process. The machines would be substantially more complex than a traditional vending machine, which would make maintenance more frequent. Collecting the cash from a vending machine might put a 14-year-old at risk for a mugging.
But imagine the machine! I don't even drink pop anymore, but if such a machine existed I might—just to see it in action.