The intent of federalism was to keep states together under a loose association through a federal government, not the same thing as a breakup of a nation. Isn’t the concept of federalism more of an American thing. My guess is that it doesn’t exist in Belgium at least not in a law-of-the-land sort of way.
Balkanization may not be the best term either, but either way way I like the idea... way too much power has been centralized over the last 100 years. And whether power is decentralized through federalism (and keeping a country together) or through break-up it’s a positive.
Even the ancient Greeks had "federalism" in their various leagues, and you could easily argue that the Persian Empire, the early Indian empires, and so on and so forth all used the principles of federalism to govern vast territories.
You guess wrong. The Belgian Constitution recognizes Wallonia and Flanders as comprising distinct communities in a federal structure. Each has its own Parliament separate from the national Parliament.
The fact that Belgians can even consider legal dissolution is evidence that they effectively have more sovereignty than states in the United States.