While some staff will be merged with other agencies to form the regime's new development and infrastructure ministry, they will very much be sidelined, taking a back seat to the new agency's core functions of housing, transport, and local government. The rest will simply be sacked. Which means all that policy expertise will be lost to Aotearoa forever, and will take decades to rebuild. Which is the point. National wants to silence the institutional voice for the environment, so they don't have to admit in their cabinet papers that MfE told them it was a terrible idea with terrible consequences. So they're going to just rev up the bulldozer and crush it all, so nothing can stand in the way of them bulldozing everything else.
Again, this dogshit vandal regime has to go. The question is how much of Aotearoa they'll outright destroy before we can get rid of them.