Credit cards took almost twenty years to gain ubiquitous acceptance. While on the surface it appears to be a simple model, it isn't. But it just works. If the analogy holds and certificate revocation tracks with credit card authorization, the technology isn't really the gating factor. It's the infrastructure required to support it. Until what the certificate stands for can be reliably verified and undone -- and the decision to status check it on-line or accept it off-line can be done seamlessly based on risk characteristics - then issuing it in the first place probably isn't worth doing.