Interesting article with great photos, but the idea that passenger service faded away and was abandoned is rubbish. Amtrak's Michigan service flourished in the 1970's and 1980's with the introduction of TurboLiner and Amfleet equipment and additional train frequencies. Amtrak and the city of Detroit invested millions in the Michigan Central Depot, reopening the grand waiting room and making numerous other improvements. But eventually, with Conrail moving out of their offices in the tower, the building simply became too expensive for Amtrak to maintain. So a new Detroit station was built uptown near the New Center, a route which allowed train service to be extended to Pontiac. I doubt Amtrak would give that up in order to move back to MC Depot.
Rich Tower
Amtrak Detroit District Superintendent 1975-1978