They switch from Terminal 7 to Terminal 1 already in April with the summer timetable.
Or are you hoping for another change from Terminal 1?
Terminal 1 is better than Terminal 7 for at least during this transition period between Star Alliance and SkyTeam. Terminal 1 has Air France, China Eastern, ITA/Alitalia, Korean and Saudia. And then there are some Star carriers and others. And in T1 there is an AF lounge and a KAL lounge. There is also LH’s lounge that can be used while SAS remains in Star Alliance. There is also the PriorityPass PrimeClass lounge IIRC.
Either way, when coming into JFK on SAS to continue on a DL flight it’s going to be an exit landslide on arrival from Scandinavia and the Airtrain terminal shuffle at JFK to get to the DL terminal.
If willing to re-clear security at JFK when having a same-day departure from any terminal at JFK, it’s also possible to go to Terminal 4 and use the Centurion lounge. Will also be possible to use the DL lounges as a business class or SkyTeam ElitePlus when flying SAS out of JFK after SAS becomes part of SkyTeam. But then you have to consider the extra time to go between terminals and the passenger security screening lines.