Could be there is a place for both volatile and non-volatile security.
Majority of customers we (Altera) have spoken to prefer the
non-volatile key and are extremely satisfied with the security. This
includes multiple military customers.

Non-volatile security provides significantly more flexibility on the
manufacturing process and enables some new royalty-based business
models that cannot be facilitated with battery back-up security.

If you are interested in further detials, here's a link to an upcoming
net seminar.
http://www.altera.com/education/net_...-security.html

Dave Greenfield
Altera Product Marketing