It would help to know the exact dates but I cannot see anything currently scheduled for April, it is possible they have some works in planning so availability of schedules on those dates are currently not released.

Either way Eurostar reservations for Amsterdam - Brussels are expensive and quota controlled for passholders, there are hourly IC Direct services which require no reservation or extra fee, they are a bit slower though.

If the high speed line is blocked on your dates then there will be alternatives, either the ICD will be rerouted or you may need to connect somewhere.

Thank you for your response! It is for April 20 and 21. Do you think if those dates aren’t showing by now I can assume they will not be available and should opt for the hourly IC?

How would I go about catching an IC? I admittedly need to do more reading on all of this.

Schedules aren't confirmed yet, likely due to works yes. I'd say that Eurostar are unlikely to run but you should avoid them in the first place anyway : 27€ mandatory reservation for such a short journey.

The IC is hourly and reservation-free. Simply show a bit early, hop on and sit wherever you want.

Thank you for letting me know, I appreciate the insight.

Am I able to take luggage on the IC? 

Sure you are. There are overhead luggage racks and also some extra luggage racks in the middle of the coach.

Thank you so much! This is extremely helpful!!

Just posting an update here in case anyone stumbles on this thread - they did just recently release times but I can see the route is a bit longer than the usual, so I am guessing there is track work and they are routing around it.