Flanders could be either an independent state or reunited with Netherlands, Wallonia could be either an independent or reunited with France, and the German-speaking part of "Belgium" can choose between Germany or Luxembourg.

German is spoken in the East of Belgium. Don't think Flemish is a separate language, it's a Dutch dialect. You can compare it with British-English and American-English.

The last obstacle for the disintegration of Belgium is Brussels (it's bilingual Dutch-French), Flanders nor Wallonia will be prepared to relinquish Brussels when Belgium splits.