Only the NS Coradia units (ICNG, the 20 8-car sets with 3 kV capability only) will run the Benelux service when ICR is gone. Currently one of them is already testing in Belgium.
M7 will be able to cross the border to The Netherlands, but as it's not 1,5 kV capable and doesn't have ATB will need to do so running at 50% power. Therefore it's limited to the border stations Roosendaal and Maastricht, similar to the current Belgian stock crossing the border. At least in Roosendaal there are plans to install TBL+ to remove the current issue that Belgian trains are running without any operational safety system on Dutch tracks.
Another issue is that the Dutch high speed line has an ETCS version not approved in Belgium and Germany, reducing interoperability. Besides the "tiny" problem of the 1,5 kV requirement to be able to call at any station (the Benelux changes voltage 5 times prior to reaching the border).