This is very useful and helpfull : Routing is going to be captured by very large centralised exchanges and (with a bit of luck) a small number of dedicated individuals (such as Zero Fee Routing on Twitter). I strongly suggest you mine his twitter feed if you want to understand what it will take to route significantly. And notice his name Zero Fee Routing. He's setting up to make money not on routing per se, but on providing inbound liquidity to merchants and others who need fat channels opened going toward them. I think this is a sustainable model for Lightning.