I think the Creedmoor is a fine cartridge and, like the 300 WSM, it clearly demonstrates the power of marketing and taking advantage of trends at the right time. Keep in mind, the Creedmoor varies little from other cartridges which have been in use for decades but just happened to come along when the marketplace was receptive and it has been pushed in just the right way. Will it surpass the 30/06, 308, and 223? Probably not. It's pretty hard to beat cartridges which were and are, US military rounds.
On another note: I have been involved in the gunsmithing trade for over forty years and know the difference between the terms "caliber (or calibre) and cartridge. However, I know that many people use the two terms interchangeably. So it is, when someone looks at one of my rifles and asks "what caliber is that?", I am aware that he is asking what cartridge it is chambered for and I answer him that way. It's kind of an automatic translation. It doesn't bother me and I feel no need to launch into a lecture on proper terminology. Much like when my wife tells me something is in the bottom drawer on the left, I automatically translate that to mean the top drawer on the right and everything works out fine. I get what I'm after and don't bother with any correction.