Very hard for BTC to become a source of income mainly because of it's variety and lack of stability and therefore you can't get it stably, and hence can't depend on it as a source of income overall.. Those working for BTC companies or doing translation professionally can probably depend on it as a source of income.
I think that making Bitcoin as a source of income is not that much difficult as you are saying, yes it is true that the price of Bitcoin is unstable but many people have made it as a permanent source source of income and their life is completely dependent on the source of income from Bitcoin, not only those people who are working for Bitcoin companies but also those people who are trading and investing their money in Bitcoin and the miners also depends on Bitcoin income.