I doubt they get de-certified. From UNESCO’s perspective, their value as a World Heritage Site hasn’t changed. But (and I say this without doing any research so I could be wrong) I doubt UNESCO has much authority to do anything concrete to protect World Heritage sites. I expect UNESCO relies on the host country to take whatever actions it can (pass laws, limit access etc.) to protect those areas. So if the US has decided it doesn’t care what UNESCO thinks, the US might also not be inclined to put much effort into protecting those areas, regardless of whether UNESCO still considers them to be a World Heritage Site.
