It does raise the question as to what impact open source software will have on programming as a profession.
None. If you can#t compete against Open Source Products, get out of the game. It's already happening, generally speaking the rate a programmer can expect to make will go down.
This is because of globalization. When you can pay 1/10th for software developed by Indian, Polish or Chinese programmers, and sell it for the same price to western markets - it's practically free money.You can't compete on salary or materials - so you need to go further down the value chain, and compete with something else. Like quality and suport. Which is perfect for Open Source.