There had been talk that Flores would jump to El Salvador, where his parents are from, after being left off of the Americans' U-20 World Cup roster. The Los Angeles born and Virginia raised midfielder is eligible to play for El Salvador, but would need to file a one-time switch to do so, which would bar him from playing for anyone else ever again. He has chosen not to do so, at least for now.
Flores was once the top prospect in the U.S. system and an U-17 star. He had interest from clubs all over Europe, including Paris Saint-Germain and Liverpool, but opted to sign with Borussia Dortmund and joined them when he turned 18. He hasn't made it past the team's reserve team so far and has seen his growth slow some. Still a prospect with considerable upside, he is no longer looked at as a sure-fire future star anymore and has seen his standing within the U.S. program fall as a result.
It's way too early to write a player off when they're 19 and that would be doubly foolish for someone like Flores, who is still involved and developing at one of Germany's better academies. While the U.S. program would hardly be crushed by losing him to El Salvador, they are certainly better off with him and, at least for the foreseeable future, they will have him.