We already have a United Earth world government - i.e. we are all ruled by big business.
So the question really is 'what type of United Earth', because that ship already sailed.
United Earth seems to be a post scarcity society in which humans are no longer coerced from birth-to-death into paying rent in the form of wage labour to their masters, in exchange for the right to survive.
But it still has 'money' (Federation credits), so perhaps beyond survival needs, Federation citizens can still choose to find employment, without coercion, in order to make more complicated products (such as Picard family wine).