So from what I can tell, the confusion is around wether the brakes use magnetic force to actually slow the train, or just use magnets to release a big rubber shoe that actually slows the train?
My instinct is that it's probably a big rubber shoe, because as much as I love the metrocars, they aren't the cutting edge of technology
Eddy brakes does seem like a good idea. I'm presuming new trains will have the train equivalent of ABS.
PS. If they wanted to go full Elon Musk, just replace the whole thing with roller-coaster technology, have linear induction motors to push the cars in and out of the stations with 3G of acceleration/deceleration. Would reduce journey times across the board!
No more worries about leaves on the line neither!
The magnetic element is primarily the application, rather than the means of speed retardation - they are still a friction device. This can be seen in the video posted above - the sparks that the application generates are due to friction between the brake shoe and the rail.
The eddy current brakes are very smart but do require some signalling hardware to be hardened due to the nature of their operation. I'd imagine we may see the new HS2 rolling stock feature these, and I believe the Eurostar e320s already have them being part of the Siemens Velaro family.
Some rail systems have been tested with LIMs. (https://en.wikipedia.org/wiki/Bombardier_Innovia_Metro lists a few, and the people mover attraction at Walt Disney World is also a good example.)