I think that "Polygyny" (males with multiple females) would be the natural order of things if white people didn't impose their laws, ethics, and moral beliefs onto people of color.
The way the economy is going, I think the wise are going to consider it as a viable way of living. It's tough to make it with two incomes today. Three incomes is a lot better than two. 
If you're a millennial, I have no clue how you're going to make it in this economic climate being solo. You can't even think about buying a house... Shit, piece of shit cars are upwards of $25K.
If you're a mature person, and can get pass jealously, there are some advantages to practicing polygyny. Multiple people cooking, cleaning, and doing other daily chores/maintenance. Multiple adults can take care of the children. Multiple income was noted above already. I can see it for some. 
For those who just want it for the perceived sexual benefits, I don't think it'll work out too well.