I've had no problems using AA lounges in April, with my CP Gold/oneworld Sapphire membership. However, the ruls are likely different for purchased Empress Lounge memberships.

After June 1, my impression is that access will revert to what it was before the formation of oneworld. I don't remember all the details, but I know it was more restricted access, possibly depending on which airline's metal you're on and/or which class you're travelling.