I was just looking at following scenario:
Some one or an rogue organisation builts up an ISP, which is multihomed over the globe with its locations, in all continents with the same AS number. Now, these bad guys would redistribute all other networks which would not even belong to them, i think you could cause a lot of trouble? All AS'es if not directly connected to each other would reroute to my rouge ISP, resulting traffic to end up in my AS --> in a blackhole. Of couse this would be a temporary condition, until found out by the other ISPs until they blocked the rogue AS. But i think this would cause some serious damage or?