Data point: The J lounge in Concourse A was open and seemed to me moderately busy yesterday when I was there 05:40-06:25. No queue for the 'proper' shower suites and – very much a personal view – I found it worth the time & effort to go to this lounge despite my arriving and departing flights both using the B gates.
Thanks again to other posters here who provided the timely steer that the Concourse A lounges had reopened.