It seems a new date of January 18 has been set to open MKA. The station will not be staffed.
We'll see how it goes, and whether it starts to hurt the Hiawatha's on-time performance. It might actually "steal" some passengers from MKE, since that stop should be more convenient to south-side Milwaukee residents.
The MKE-MKA fare is expected to be six dollars, as reported
here and elsewhere. I don't know if there will be a fare difference from Chicago to MKA, vs. the $20 tarriff to downtown Milwaukee. It's currently not yet on the amtrak.com reservations page, though it should be very soon.
Naturally, I will be out of town (on a train, no less) when the first train runs.