Objectively, the .222 Rem is a delightfully accurate cartridge that dominated Benchrest competition until it was displaced by the 6x47mm and 6mm PPC cartridges.
The .222 Rem is alive and well in my household, and will remain so as long as the brass is available.
Today, the .222 Rem is still highly appreciated by knowledgeable varminters for its efficiency and accuracy.
The .222 Rem is not an obsolete cartridge, though it's past its peak of popularity.
I don't have any experience with the cartrige but the .260 Rem is .308 case necked down to a 6. 5mm bullet as opposed to the .243 which is a 6mm.