I think a big storm of a unexpected form is brewing for toolkits like ACS or the internet infrastructure in general: it's anonymity. Anonymity on the internet or digital identities and monetary transactions computationally proven to be anonymous (not just secure and encrypted) will challenge ACS 4.0 and on wards. Big revisions and complete rewrites will have to happen when we take the idea of permissions and groups to a higher level. Otherwise insurance companies and the FBI can just call up your local ISP and start making backup tapes of every little ACS boxes at the cohost. RDBMSes can be dangerous in the wrong hands.
