Although you’re cutting it dangerously fine with Hamburg or Freiburg. You could get an onward flight from BXL to any number of places I suppose. This is all a bit Simon Calder, sorry.
I reckon if you buy an early morning Eurostar to Lille or Brussels for the morning of March 7, there is a 7/16 chance of being able to get a connection to the match, wherever it is. Possibly 8/16 if it’s possible to get to the Wankdorf in a day from Lille.