Indeed. Was already in de Volkskrant on Saturday. Long story short, at the Parliament of The Netherlands, there are discussions at the moment on the new 2025-2033 concession. If the Parliament agrees, the concession of NS will be for a large part of the Dutch railway network with NS keeping it as monopoly, including Amsterdam - Brussels.
However as SNCB/NMBS and Eurostar are partners of NS, they are all allowed to operate. But if Qbuzz starts to Paris, they won't be allowed to sell tickets between Brussels and Amsterdam.
As this concession isn't signed yet, it is kind of a last chance opportunity for Arriva.