I can think of many other roles one could go on to fulfill. Take Runescape as(a very poor) example. Yes the premise of the game is MMO battle, but you don't have to, you could be a miner and sell raw minerals, you could be a crafter and sell armour/jewelry/weapons or even a chef and sell health(effectively)
So other occupations could be taken by players; breeder, compeditor, might be able to chill in the audience of competitions and offer their opinions, pokeball crafting(based on a skill maybe?), etc(I cant think of more right now)
This is a great idea in my opinion. but my opinions on forums tend to be shot down for being too difficult or outlandish