I had to ride the mainline in and out of work a few times this past week, and watched the aftermath in progress.
Starting with my commute home Thursday, we rode right next to the train. All 8 of the M7's looked in really bad shape underneath - a lot of the wheels, trucks, third rail shoes, and struts looked really rough.
When I rode in Friday morning, about half the consist had been removed. Looks like whatever was roll-able got dragged into the Hillside / Holban Yard by one of the switchers (did it have the right coupler??) My guess is the other ones needed to be flat bedded to Hillside or maybe even Arch. I saw perhaps 2-3 cars in the western leads of Hillside and about 4-5 cars at the site. And yes, it was the first time I ever saw an M7 pair separated.
When I went home that afternoon, the cars were all removed and there was a lot of workers on the track inspecting everything, so I wonder what they may have found. From where I was on my train, the only visible damage to the track was some of the third rail and / or guards were largely dislodged. Hard to tell any more from that angle.