Don’t stop looking for your family in a town just because they don’t live there anymore. They may still own property there, have business partners there, or may be heirs of people who stayed behind. In notarial records, I often find references to children living abroad, for instance when one of their parents died and their estate needed to be divided.
If your ancestors emigrated from the Netherlands while one of their parents or unmarried siblings was still alive, make sure to check the death duties files for these relatives to see if your ancestor received a share of the inheritance.
Good advice, and it’s nice to see the map of my hometown!