Regarding the irreplaceable programmer, this is a Bad Thing for everyone involved. It keeps the programmer stagnant, mucking around in the same old code-bog. It keeps management fearful of losing the programmer, taking away some of thier motivational options. As Weinberg suggests, when a programmer becomes irreplaceable, it's time to replace him.

The company may lose some productivity in the short term, but in the long term it will be better for all involved if they let him go. The company will have learned from its mistake and will always keep more than one programmer trained on the system. When the programmer finds new employment, he will be faced with a new system to learn and hopefully this will bring about a new wave of motivation to increase his knowledge.

The fact that he's well liked makes the firing more emotionally difficult, but a good manager should be able to put those emotions aside and make the right decision for the company.

--Dave