The quick version
Sacked Norm Smith
Factions
Ron Barrassi left
Factions
Never became a professional club
Split from MCC
Factions
Voted to merge
Factions
Gave Scully Barassi's number
Scully left
Currently
Most Demons supporters today were alive in 1964
Good summary.
The main thing you forgot to mention was the development of the Range Rover 4WD. This enable Melbourne supporters to flock to the ski fields in luxury. Hence their vocal support at games dwindled. With little vocal support, the team performances slipped.
From Wiki...
"The final design, launched in 1970 with bodywork styled largely by the engineering team rather than David Bache's styling division, was marketed as 'A Car For All Reasons'. In its original guise, the Range Rover was more capable off-road than the Land Rover but was much more comfortable, offering a top speed in excess of 100 mph (160 km/h), a towing capacity of 3.5 tons, spacious accommodation for five people and groundbreaking features such as a four-speed, dual-range, permanent four-wheel-drive gearbox and hydraulic disc brakes on all wheels."