I still do not see this as a reason to remove Dining from Prestige. Even the free Preferred card offers 2X points for Dining and Entertainment, as do the legacy Forward cards. Dining keeps the card in the wallet -and- it creates a situation where a cardholder might discuss it with a friend or colleague.
Per Gary @ VFTW, Citi rep confirms July 23, 2017, end date for Prestige Admiral's Club access and denies the removal of 2x for dining (in other words, 2x for dining will remain).