Yes you are correct, Farnborough has a great history behind it.. Way before I was born..
Having flown from the airfield as a Flight Observer with the Ministry of Defence from 1985 to 1994 the airfield now belongs to TAG who are a Civilian operator.Since the MoD sold the airfield to TAG they had to make number of changes to comply with the Civil Aviation Authority which the MoD had got away with.
Now the surrounding area is being developed, More and more houses are being built, More companies are moving into the Farnborough area which means more people. This in turn has complications for planning & coordinating an airshow which also has rising costs with insurance premiums.
The airshow itself has rapidly reduced in numbers, Not so many aircraft on flying display or static. This I believe is due to other airshows Like Paris being every other year and up and coming shows like Dubai and one or two other trade shows I cant think of.
So there you have it.. There is talk of moving the show somewhere else within the UK but all this hopefully is sad rumours and speculation.
regards
Adam