To call the train service from Truro/Plymouth high speed is pushing it a bit, and that's before part of it falls into the sea without hope of replacement in a few years time.
Sadly Cornwall is of no importance to London in the grand scheme of things so the airport is going to have to stand on its own two feet or die. Cornwall CC should ditch it and use the subsidy money on things with a broader benefit to what is a very poor area. The private sector will either make a go of it or shut it.
Bad news for the region and businesses within it, but a harsh reality of the times - its all about location, location, location, and if that doesn't equal maximum return per £ invested then forget it. Social infrastructure for the benefit of all doesn't exist anymore.