To be clear, the restoration was largely a private endeavour, driven by Ford Motor Company who purchased the building.
Ford is putting its one of its business units in the office floors.
Currently, the station has no train service at all, as it was abandoned and left to rot for decades, Amtrak decamped to a small facility in midtown Detroit.
This is where Amtrak currently stops:
View attachment 571403
The above from Streetview, below an interior shot w/credit in the image:
View attachment 571404
***
Ford has done the restoration work in such a way that the main level of the building can be open to the public and it could see some train service again in the future.
Amtrak is contemplating a return to MCS when it launches Detroit-Toronto train service. Discussions are under way with Ottawa to accommodate customs services at a Windsor Station (maybe not the current one); with Amtrak tenatively hoping it can launch the service Q3 2027. (not sure they'll make that timeline, but here's wishing them the best)