Either way, when it comes to the question of making money, I think one of the first questions is to what scale? I guess more to self-reflect by the individual is "how much do I want to grow before I wish to stop growing" or in the more enlightened form, "at what scale is my happiness best achieved"? I believe most people are in the best position to pursue happiest when they are part of an operation that lies within the boundaries of their capabilities all the while being able to provide aspirational mobility. Depending on that aspirational mobility, this is where the money comes in. It is easier to make the money if you are specialized or focused on a limited range of products. This is a universal truth, but this does not argue at all against sustainable farming.
Variety to Scale
I guess to compare and contrast this dilemma it would be easier to explain by comparing Joel Salatin's farm system to Sepp Holtzers. On the whole, both are sustainable more or less to a degree, but one is significantly more to scale while the other has more variety. I just want to put that out and take in any opinions on the matter regarding the vices and virtues of (sustainable) scale and variety.