Flex dining came to the Lake Shore and Capitol Ltd in June 2018. Because of the overwhelming popularity and nothing but kudos to Mr. Anderson for introducing this vastly improved dining experience it was expanded to all the Eastern trains and the Texas Eagle. (By the way,in case anybody didn't know,that was sarcasm)
Sarcasm notwithstanding, that is not the entire story of what happened. It all started with the delays in the delivery of Viewliner Diners from CAF.
The Heritage Diners came upto a point where they were due for a very major overhaul, and Amtrak decided not to spend that kind of money on them for what they then believed was just a few months of additional service. This led to both the Star and LSL losing Diners. The Star at that point lost dining service altogether. LSL got a truncated Dining service served out of the Amfleet II Lounge/Dinette.
These over a period of time were variously called Contemporary Dining and Flex Dining, with appropriate incompetently done marketing hype attached, generally blaming the whole thing on Millennial's alleged awful taste, while carefully hiding the real reason - which was not enough serviceable Diners available. In parallel there was an exercise afoot to meet the Mica induced goal of removing F&B losses, leading to the spread of Flex to all Eastern trains.
Meanwhile the Viewliner deliveries got delayed for years making the situation more and more precarious, until when things were approaching breaking point, the Viewliner Diners finally arrived. But by then the Mica induced move towards Flex was in full swing and all Eastern trains had gotten Flex Dining.
And then for some unknown reason (well actually it was a decision to not spend money doing basic maintenance and inspection since Flex could be served out of Amfleet II Lounges I suspect) Amtrak parked 7 of the brand new Diners so that even as they restored Dining Cars to single level trains as the much ballyhooed Sleeper Lounges, it became necessary to withdraw them from one, and this time they chose the Crescent. But since Flex Dining was in place, that was not a problem since that could be served out of an Amfleet II lounge/ Dinette as it originally was designed to be served.
Strange are the ways of Amtrak!