My understanding from briefly talking with one of the leaders of the Hard Hat tour I enjoyed yesterday was that this lounge will have an annual access fee (amount to join not specified), or a day pass for $20.
Another member of the tour group asked if it will be run by Amtrak, or an outside concern, and at the moment, an answer could not be provided.
It is not a BC or Metropolitan-style lounge, as anyone may pay to enter-Metra commuters or Amtrak passengers. At this time, I would not expect pre-boarding, etc.
IIRC, it will be open until early in June, with free access, though as of last night, the furniture had been moved back into place, but I saw no sign of the Bar.
I'll be in CUS again fairly soon, I'll report back with any news.
Mike