Nothing in this Wikipedia article talks about government defaulting on bonds (or they expiring worthless) if the economy enters into 5 year long recession.

Default should be an unusual or unexpected outcome, not part of the contract. You don't take a loan from somebody and then saying them: "you know what, if I will not return you money in 5 years, even if my company still operating - write it off."

If the expiration is part of the contract, then it's a derivative contract. In this case you have only 2 outcomes: either you get paid 1 basiscoin, or your "bond" expires worthless after 5 years and you get nothing. That's why it's a binary future. Binary futures/options and prediction markets are illegal in US since they resemble gambling.