Part of the Filton site has been sold off for housing and the runway is to close at the end of this year. Aviation and aerospace industries will continue at the site and in neighbouring ones though.
The City Airport proposal came far too late. If BAe (or a predecessor) had been awake in the 1980s the airport could now be similar to BHX, as suggested above.
I realise that aerospace industry is not necessarily tied to a runway, but where it is there are infinitely more opportunities for it to flourish and grow. What an utterly foolish decision to close the runway.