You know the next time something like this happens (and, this is software, it will happen), there will be a lot of people trying this attack. It was theoretical

You know the next time something like this happens (and, this is software, it will happen), there will be a lot of people trying this attack. It was theoretical before with "enough effort"; now, it is known to be easy. And the problem will get harder to manage as BC becomes more popular. They could restrict damage because the ecosystem is still small, but when if there are millions of merchants? The alternative is centralized processors, which doesn't make BC that much better than cash.