Implications of partitions on read.consistency_level=all and write.commit_level=all and AP (re CAP)

What will be the outcome if read.consistency_level=all and write.commit_level=all is used and one or more replicas are not visible? Does all then translate to all visible, or will transactions fail effectively resulting in CP system?

Please see Understanding Consistency Level Overrides which will explain how these behave. But basically the answer to you question is no, these settings will not result in a CP system.