Hello esxi1979
Is it possible to move the vCenter somewhere else during this process? It would likely make many parts of it less hassle and cleaner.
So, before starting any of this take backups, ensure the cluster and all data is healthy, the pertinent areas of vSAN Health are green, all VMs are powered off and there is no resync, you could also consider placing all nodes in Maintenance Mode with 'No Action' option to ensure no possibility of any data getting changed/updated on only 2 of the 3 nodes which can essentially mean the data is FTT=0 (until it can sync the changed data to the 3rd node) - you can use a shutdown script to do this (VMware Knowledge Base all the steps here but without the reboot).
Before changing the vSAN network, make as best possible validation that the network you are migrating to will work based on your configuration - common pain-points here are: (where applicable) MTU not supporting 9000 end-to-end (even though your network guy swore it did), badly configured or misconfigured LAGs, VLANs not existing or configured correctly (even though your network guy swore they did).
You should be planning to do the ESXi name changes as a seperate task as this requires removing and re-adding the hosts from vCenter inventory and the traditional way of doing this is to also pull it out of the backing vSAN cluster also (but you can actually workaround this with some workaround steps e.g. that it gets removed from vC and vSphere cluster but stays in the vSAN cluster):
Hope this helps, give us folks in GSS a shout if needed.
Bob