Nice idea, but.. I work with Single Sign-On setups for multiple companies, where both sides of the fence have a certificate which needs to be valid according to

Nice idea, but.. I work with Single Sign-On setups for multiple companies, where both sides of the fence have a certificate which needs to be valid according to well known CAs, and they have to be manually renewed. So a 3 month validity is a non-starter - the cost of buying a 1 or 2 year cert is far less than the cost of manually updating every 3 months.