If another big mining pool goes down we may be looking at 40 mins between blocks maybe even longer - transactions are not processed if no blocks are solved.
Statistically, even if hashing is at the target rate then once every 48 hours there will be at least one block that took an hour to solve.
And if your pool suffers technical issues those miners will switch to another pool.
As far as this being a problem if hashing capacity drops below target and that persists for a couple weeks ... there is little difference between six confirmations taking an hour versus six confirmations taking two hours.
With most of the costs for ASIC mining being fixed (i.e., for the purchase of the equipment), there is little reason why hashing capacity would drop dramatically.
Man if 50btc goes down how many other mining pools could cope with that surge of users - It is quite likely the other pools would be knocked out from the sudden increase in traffic further compounding the problem.
Plus with all the DDOS protection they now run - it is quite likely it would kick in as it would see the sudden increase as an attack.
So at 10 min intervals it can take 1 hour every 48 - OK was not aware of that. Using the same argument if the interval jumped to 30 mins then every 48 hours it could take over 3 hours?