WAAAAAAY to complicated and needs to much time.
1. Set Host into MM
2. Migrate one VMNIC back to a vSS and migrate the Management VMK to thats vSS. You can remove all other Uplinks NICs from the vDS when you dont run iSCSI/NFS storage
3. Shutdown the Host and add/replace the NIC
4. PowerOn the Host and within DCUI assign the new VMNIC/same VMNIC ID to ESXi Management. One NIC is enough at this step.
5. Assign the VMNICs as Uplinks to the vDS and migrate the VMK
6. Leave MM
There is no reason to remove the Host from the vDS, Cluster or even vCenter.
If you use a LAG/LACP than a lot more is needed but it depends on if you add or just replace a NIC or can re-use a existing 1G NIC for temporary MGMT.
Regards,
Joerg