The licensing. My God, the licensing. It's not so much the money, as the infernal, mind-bending tax code level complexity involved in making sure all your software is properly licensed: determining what 'level' and 'edition' you are licensed at, who is licensed to use what, which servers are licensed... wait, what? Sorry, I passed out there for a minute when I was attacked by rabid licensing weasels.

  I'm not inclined to make grand pronouncements about the future of software, but if anything kills off commercial software, let me tell you, it won't be open source software. They needn't bother. Commercial software will gleefully strangle itself to death on its own licensing terms.