The actual services agreement was titled “recreational services” and nowhere was internet gambling mentioned. The Wire Act, the Travel Act and the Illegal Gambling Business Act are laws that carry stiff penalties. The WTO notion that the United States would agree to trade services deemed illegal by its own laws is absurd.
On contracts: Providing online gambling is illegal per U.S. law, thus any contract is unenforceable. Contracts based on illegal activity cannot be enforced. I believe this is true in most countries.