VdG
I wouldn't put money on Cambridge loosing its airport to houses. A growing High Tech city needs good communications - road,rail and air. Luton and Stanstead are getting pretty busy and Biz jets may find it easier to operate out of Cambridge especially if there is a smart new terminal.
As for houses, they are going to build at Oakington and improve the rail network to get people into the new business parks in the west of the city.