The Flyers none NHL prospects are fairly weak. None of the wingers are legit prospect and Nick Cousins another center is probably the next best prospect at center. After him on defense Gotisbehere, Hagg, and Morin are the only true NHL caliber prospects but they are all project players.
Their best young assets are all already in the NHL (Giroux, Voracek, Simmonds, B. Schenn, L. Schenn, Gustufsson, Couturier)
Though if it's worth noting Philly is prone to having surprises Read was unexpected. And now Raffl has 8 points in his last 11 games.
But if you are going by scouting reports Laughton is really the only big looking prospect.