I don't have a full answer, and acknowledge that this will be a difficult transition, but humanity had lived for millennia before the modern concept of "a job", and many tribal societies still do, so we know it's possible.

As for "happy", I don't think humans will ever be generally happy, but there's nothing new about that - our neural chemistry keeps us at a state of want as an adaptation; c'est la vie. As I see it, if you want something resembling lasting happiness, you need either drugs, or to relinquish "the self" via deep mindfulness, or to engineer ourselves beyond being human.