Never going to happen.
Just think of the number of votes of every householder in the M4 corridor whose property will be devalued?
Just think of the behind the scenes lobbying power of every business in the M4 corridor whose airport will disappear?
How many companies with regular international links will consider that moving away from the UK is better than trying to move across London? They would be going to a rather large building site where the new business parks are being hurriedly put together and an airport that may, or may not, meet all the hype for connections and where are all the new houses for the staff who are going to have to be paid to relocate?
Never going to get off the paper.