It should take 10 minutes with a transaction fee that isn't too low and with a few measures* instant 0-confirmation transaction can be relatively safe and used for transactions of, say, less than $1000 (given the resources required to double-spend if appropriate precautions were taken by the merchant, accepting 0-confirmation transaction for low-value goods can be safe).
*connections only to previously whitelisted and known honest nodes, no outgoing connections (UPnP off), etc.
Lets not forget the other strength of scrypt base crypto called litecoin. The difficulty re-target is much more quicker. I always have seen litecoin as the little brother of bitcoin but if this hypothesis is true then litecoin could be come the new bitcoin. I can seethis happening if the barrier of asics not being able to mine litecoin is circumvented. Litecoin was considered gpu proof at one time.