Well if Gatwick became a "perfect hub", why would public transport matter as all the pax would be transiting...?
I said second, never perfect! Two entirely different concepts
Even if Gatwick, Fantasy Island, BHX, or Blackpool (NW coast)??? - were to become the biggest hub in Europe at the time of opening, you still need to deal with O&D traffic. There is no airport in the world that only operates on a hub basis with ZERO O&D. There are two railway stations in the British Isles that work this way, but they are very unique cases!
Even if we take somewhere like DXB as your definition of a "perfect hub" - on the basis it has 380s coming in from Europe and 380s going straight out to east Asia and Australasia, aswell as smaller a/c - there is still a significant city that has been built on the back of this airport existing.
And when some indeterminate point in the future arrives, we'll know who was right.
Well actually, that also translates as "let's agree to disagree". You can't make policy based on saying "let's see who is right in 20 years". We have to look at what we've got now, what we're likely to need, and the best ways of meeting that need.
there has only been one enquiry that looked building an airport in the Thames Estuary
I never said enquiry, I just said proposed and rejected. The 2003 White Paper quite clearly included Cliffe as an option, and rejected it very strongly.
it will mean that London and the City will be well on the way to becoming irrelevant backwaters
Please re-read what I said. My point was that aviation as an industry isn't going to keep growing forever, and certainly not in its current form.
The cost of fuel, and the pollution it causes are two huge challenges the industry faces. My personal view is that in the long run, the market for flights within the mature European and North American markets will grow slower than the rest of the economy. The emerging markets will continue to emerge, but they will still only make up a small proportion of the pie.
Now this is where there is an element of crystal ball gazing, but we have to go with the trends we know are happening. A third runway at LHR would allow for an element of growth, whilst the other airports could also continue to handle the loco traffic.