It’s been a year since Costco and American Express announced the end of their longtime partnership, but the two parties are taking longer than expected to finalize their divorce. The original spring end date has now been pushed back to June 20th, after which Costco will stop accepting Amex cards and start accepting Visa. If you already own a co-branded Costco/Amex card, watch your mailbox for a new card from Citibank Visa — this time with an even more generous cash-back rewards program.