I'm reading a lot of conjecture in this thread.
I can fully believe that Citi may purchase the customer base from AmEx if they come to an agreement to do so. That would fall under the parameters of the agreement you have with AmEx. But take over the balance, no way. An individuals credit history in regards to the card will transfer? Uh-uh. Not gonna happen.
You want an AmEx, fine, here are the cards we're offering and a nice shiny new hard hit on your credit to make sure you qualify. You want a Costco Citi Visa to replace your Costco AmEx? Just submit an application and we'll do a hard hit on your credit report to see if you qualify.
I think some of you are forgetting that getting a Costco AmEx was an option, not a requirement. I've already talked to AmEx and they offered me a replacement card if I wanted it. Offered is the key word. I called about a fraudulent charge but once that was settled, I got the pitch for a replacement card. I was told that they expected a huge amount of activity regarding replacement cards and were strongly suggesting it be done sooner rather than later. They can't just automatically issue you a replacement card and even if they could, they'd be crazy to not do their due diligence as it relates to your financials. And Citi cannot just automatically issue you a Costco Citi Visa to replace the Costco AmEx. Once again, due diligence. Plus, I bet it's illegal as illegal gets.
Remember, we get credit card offers in the mail, not credit cards themselves.
I may be wrong about this, but if so, I bet I'm not far off.