The more constraints you put on changing government operations, the harder it is to implement and the greater the likelihood is that there are unexpected outcomes. In the case of attrition, based on what you described, that's certainly a possibility.
I would say more broadly, because there have also been statements about looking at lower-priority areas or less efficient areas, that attrition is potentially part of that. I don't know, but that approach is typically.... When you look at other jurisdictions, that's what they encourage you to focus on.
I know everybody's read the Prime Minister's mandate letter with the seven priorities. He's been very clear that he expects the entire public service to be focusing on those priorities, and if you're not part of those priorities, you'd better figure out how you're going to be contributing to them. Typically, that's a better way of going about things. It's an easier way of going about things, especially if you want to implement a lot of change across government in a very short period of time.