Can GA ever be economically viable, YES but only if owns and controls the assets and we are talking about licensed airfields not farm strips. The current difficulty has happened because a great many well heeled pilot owners have not had the foresight to invest in the airfield they use, they have been quite happy to take advantage of the landowners generosity and have cheap flying.
Owner operated airfields are always going to be vulnerable, however enthusiastic and committed they are, they get older and their family will always want to maximize the value, that will also include local authority owners because policies will change over time.
It only needs a group of keen pilots who have enough foresight to get together and buy an airfield, they all could probably buy their own farm strip, so why not invest in a proper airfield. Long term airfields and land in general have proved very good investments, the annual income is small but capital value has increased massively - and will continue to do so because they are not making my more. There is never a right time to invest you have you take a risk just like every business, now is the time to stop whinging and get together.