According to jona970318 American Express is set to announce a new Centurion lounge will be opened at Washington National Airport (DCA). In addition new expansions for SFO & SEA will be announced. It’s not clear where the new DCA lounge would be located at this stage but Jona speculates it could be landside in the B/C area.
VFTW notes that the SFO expansion would bring the size to nearly 16,000 square feet and the SEA ‘expansion’ is a relocation that would go from 4,500 square feet to 13,700 square feet in space.