Miners signalling they have upgraded by flipping a bit in the nVersion field has little relevance in a hard fork. If 100% of the hash power indicates they are running this proposal, but the nodes don't upgrade, what will happen?

For the record, I actually talk a lot about hard forks with various developers and am very interested in the research that Johnson in particular is pioneering. However, I have failed to understand your point about 95% miner signalling in relation to a hard fork, so I am eagerly awaiting your explanation.