Despite SJ not running the Berlin-Hamburg-Stockholm night train any more from August 2026, the German company that owns the carriages - RDC - intends to continue on its own https://www.rdc-deutschland.de/de/presse/pressemitteilungen/rdc-deutschland-gruppe-wird-nachtzug-berlin-hamburg-stockholm-fortfuehren/
Still some open questions, but this is good news! #CrossBorderRail