Back when, when cornies were the state of the art for soda, they used to do the exact same thing, especially for large get-togethers. Line up 3 or 4 cornies full of the same product, and run connector hoses fron the gas-in, to the soda-out connectors. At one end of the line, a Co2 bottle, pushing the whole rig, and a spigot (usually a jockey-box) at the other end. Wouldn't run out, until the last corny ran dry.
The only thing it would save you, is you wouldn't have to switch out the cornies, until you ran the last one dry. As for mixing beer, I don't think it would mix properly.
steve