Interesting, TGG, but it's hundreds of years too late to apply these ideas to the Cornish. Who are the Cornish? How would you recognise a Cornish person amongst a crowd of English people? If you can't recognise them, you can hardly discriminate against them, hence they are not recognised as a group under the Race Relations Acts (or whatever they're called these days) and the criteria are very flexible, including e.g. "New Age Travellers". But the Cornish don't have a distinct physical appearance, lifestyle, language*, religion, manner of dress etc. etc. Possibly they did once, but by now apart from a few rather self-conscious institutions like the Gorsedh, they've pretty well been assimilated into the mainstream of 'Englishness'. Some have a local accent, there may still be the echos of a few local 'folkways' and events (many arificial (re)creations), but that's true of many other parts of 'England', from Cumbria to Kent.
[* Obviously the Cornish language still exists and is learned by a few hundred people each year, but these are as likely to be incomers/outsiders as "true-born Cornish" (whoever they might be). Since there are no Cornish speaking communities no one can really claim the language it as part of their "native culture", it's just a hobby like any other (local history, steam-engines ...) ]
As for Deacon's book, well what is there to say that basically wasn't said, and said very clearly, back in "Cornwall at the Crossroads" however many years ago. No one took much notice then, why should they now? We've probably gone well past the crossroads by now. Is there really much Cornwall left to save? There seems to be no will to take political action, look at all the massive protests that didn't happen when the petition for an assembly was binned by London. Look at the tiny percentage who vote for MK, about on a par with UKIP.
It's no good bleating on here about 'genocide' TGG, (apart from anything else, I don't think anyone else comes here anymore), the way to turn things around is, or more likely would have been, to set up the necessary structures and institutions (political, economic, co-operative, educational ...) to define Cornwall as something different and develop alternative visions. Where is the government-in-waiting? The fund to buy back the land? The embryo of a local economy? Home-grown approaches to education? etc. etc. They don't exist, people would rather rant about 'genocide' than do anything positive.
Scotland may well become a nation again, Wales will be left on a knife-edge (could get more devolution, could get less), but Cornwall is probably a lost cause, although I get no pleasure in saying so.