If you watched any of the CONCACF U-20 World Cup Qualifying tournament, Emerson Hyndman was one of the bright spots for the USA. Once the squad switched to a 4-4-2, Hyndman was given free range to roam and bossed the midfield in most of the matches. Against an overmatched Aruba he looked like the second coming of Zidane.
In the final minutes of the clinching qualification game against El Salvador, he came off with an injury, which is now being reported as a broken collarbone. If this is confirmed, he would expect to miss six weeks and not make his return until April.
Fulham have made moves to solidify their midfield, and his presence might not be missed that much in the short term. Between Ryan Tunnicliffe, Alex Kacaniklic, and Seko Fofana; enough players have been brought in to cover his absence. This also doesn't take into account Tim Hoogland and Lasse Vigen Christensen returning from injury.
However, this is important development time in his career. With his contract expiring in June of 2016, Fulham won't have as much time to evaluate him in game situations before deciding whether to offer him a new contract. It may be my American biases talking, but I'd offer him the contract now. I think he's shown enough in his limited first team time and with the various USA squads to show he's worth it.
Fulham were not required to let him join the USA for this tournament, and took a risk by doing so. Unfortunately those risks came true. Hopefully he'll repay the kindness Fulham have shown to him by signing an extension. He may be too good to stick around for more than another season if Fulham remain in the Championship, but at least this way Fulham would receive compensation if he goes.