If it were, they would sell off the brand to a smaller producer and see if it sinks or swims.
That would be a risky move, because older people who didn't hear about the sale would still associate the brand with Coca-Cola.
It also might be the case that no smaller producer would want to pay for the brand because the only thing it has going for it is the distribution network. If any brand has negative equity, it's Tab. (Also, the market share of diet sodas has been shrinking over the past 20 years or so, in favor of energy drinks and specialty juices.