Do you disagree that OCSP would be significantly less costly and complex if the responder URL were not included in certificates, freeing the responders from having to serve hundreds of millions of clients?
Even that really depends on what the "SLA" expectation is. How many QPS would we be required to support before we're allowed to start dropping queries? If there's any possibility of a burst beyond what we can handle locally we'd keep the CDN, so maybe the CDN bill would be significantly smaller on account of lower volume but all the complexity and care of operation would still be there.