Comparing LAX’s ops to JFK, that will hopefully be sufficient in terms of capacity. JFK has dozens of long haul flights leaving within a few hours of each other (+JFK and SFO). I think DL just has 1x: CDG, HND, SYD, AKL, BNE and PPT (and some of those are not daily) + JFK?
I can see VS passengers using the new lounge until the new Clubhouse is open (and for some, even after) since UC check in is now colocated with DL, but for JV partner passengers, it will be a bit of a hike so many may not choose to walk all the way over.
Issue is that there will be no 3 hr rule, maybe with no spa leisure travelers will not arrive 6 hrs prior to the flight such as the WSJ reporter who recently wrote up the JFK D1 lounge. BOS will be even smaller at 6,000 sq ft.