I've worked in estimating on very large infrastructure...

I've worked in estimating on very large infrastructure projects in the past. Getting the budget 'right' is an almost impossible task, there are so many variables that happen when construction starts let alone pressure from management at concept to keep the budget at a certain level. There would have been contingency based on worse case scenarios which have been exceeded here.

Changing project management can have a positive impact if things have been getting sloppy. I would imagine there were a number of heated meetings and likely on a personal level considering their positions held, that's how I read the comments on culture etc. Also likely under reporting the cost over runs to the board in relation to the communication comments.

Someone else will fill the role, the project will be delivered and life will go on however this will obviously be a large hole in the coffers that will impact wider business operations. Not taking incentives is a positive on leadership ethos IMO. Taking this action is also a positive step IMO, shows that they are trying to this back under control. Does it devalue the company? probably in the short term but the profits they are making dwarf the cost over run currently. It is still a large financial set back none the less.