I just found out RedHat (and CentOS) are implementing some changes in the way they name devices:

https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/appe-Consistent_Network_Device_Naming.html

This will effectively mean that after an upgrade to version 6.5 of the OS, some installations will suffer from their network interfaces being renamed. Zabbix will simply use LLD to create a new item in the host, and then expire the old one after the "Keep lost resources period" passes.

It would be very valuable to have some sort of 'Merge item history' option that can take the statistics of two items in any given host, and then merge them together into one. The item with the oldest metric would change to the itemid of the new one, but perhaps the user can be given the option of doing it the other way around.

I can see some potential issues with this feature, like checking that the item data, value types and things like that are consistent; figuring out how to consolidate existing data for the same period (perhaps the user can decide 'NEW overrides OLD'); or how are trends recalculated. But I think all of these can be sorted somehow.