2. Mining Hubs: speaking of mining hubs, GHash.io and the others all depend on physical hardware to do the mining. In the event the center is compromised or physical hardware damaged there's not much of a failover for this. Unlike data which can be backed up in a redundant data center in another city, these hubs are susceptible to many types of disaster.
Miners should have set up a few failover pools (easily done with cgminer or bfgminer), so that when the primary pool is down, the hashrate will be pointed to secondary pools automatically.
So, problems on one or a few public pools shouldn't cause too much problem...
The pools are also generally located in diverse places throughout the world so in the event of a disaster in one area there is a very small chance that another pool would be affected by the same disaster.