I don't think they ever envisaged how popular AMS would be from DND, especially not when they built the terminal. I doubt they will expand the terminal as there won't be any demand. They may somehow rejig the current building to make some more space airside.
Having never flown from DND (only to DND once when it was linked with BHD) I am quite excited about my upcoming AMS flight in a few weeks. I booked it as soon as they went on sale and got it for £48 return, so a good deal. Is there anything airside at all? I can never find any pictures of how the departures area looks. Where is the immigration/customs area? DND has only ever had the odd charter from Spain, so having a scheduled, daily service must have made them create a new area surely?