The problem with cobranded cards...

[TheGardner]

I think it depends on how the contract was written. Most Co-Branded cards belong to the store and transfers to the new managing bank.

Costco is a little different perhaps as they have a network contact and the card isn't a "Costco " card in name. Not sure how it is written.

[asot6]

This is huge for me because I have been eyeing the TrueEarnings card for quite some time, just got the Discover IT in October, Sallie Mae World MasterCard in November, and have been anticipating applying for this in December.  For me, it's a win-win because I'd like the 2-in-1 deal where I could carry an Amex and also have it be my Costco membership card.  I just confirmed with a rep yesterday there that even should the relationship end, I would have the ability to backdate since this would be first Amex card and since it's issued by Centurion. Honestly the rates aren't all that--sure I may use it for the rare occassions I get gas there, and the 2% for restaurants is nice, but the way I look at it it's a way to get my foot in the door with American Express. Also, since I have the Executive Costco Membership, I'm basically doubling the yearly reward I would receive (for free). 

The EveryDay as well as BCE just aren't enough for me to move in that direction.  I have been looking at opening up a Fidelity checking (free ATMs) and the Fidelity Amex would be 2% cashback on everything, but I've heard it's not issued by Centurion thus would not be a good first Amex card (can't backdate).

[Gunnar419]

If it works the same way in the U.S. as it did in Canada, the TE card would (in the words of one credit writer) "become an ice scraper." In other words, the TE would simply go away. However, it seems very likely that Amex, not wanting to lose those millions of cardholders, would offer TE holders a substitute card or perhaps create a new card with similar benefits to the TE.

I don't know this for sure and I've been unable so far to find out what Amex did in Canada, but it seems likely.