Update: Chase Bountiful & American Express Bevy cards have been launched.
A few months ago Marriott registered trademarks for Marriott Bonvoy Bevy & Marriott Bonvoy Bountiful. Gary at VFTW now has a leaked image of the American Express Marriott Bonvoy Bevy (this card name is also listed on this page).
It’s expected that the Marriott Bonvoy Bountiful will be a new Chase card and both new cards will be midrange cards and come with a $250 annual fee with the annual fee on the Bonvoy Brilliant card being increased to $650. American Express has previously sent out a survey regarding changes including the annual fee increasing to $650.

