You will need to unregister those VMs from inventory as well, and that has some implications depending on what all you're using in your environment. But, yes, assuming you can 1.) power down; 2.) unregister VMs; 3.) remove NFS mount across all hosts; 4.) re-mount using correct IP/hostname; and 5.) the NAS allows you to mount with the same permissions, you'll see those VMs. There will not be any data loss. That said, any time you start messing around with storage, the strong recommendation is to err on the side of caution and ensure you have a full backup of all VMs that reside on said storage.