re: Is there any chance Landon D will ever play for the nat team again?

Sure, there's a chance, but it seems doubtful at this point. His exclusion from the World Cup demonstrated JK's thoughts on Donovan, so it seems highly unlikely he'd be asked to join the team for any meaningful competition in the future. If he's asked to join for a friendly, Donovan would decline I'd imagine. He might decline outright for any invite.