The former Bordeaux was given a start in United's Champions League defeat to Besiktas on Wednesday night.
Ferguson said: "I think that the values and trust we put in them by playing them, tells them how high we regard them — they're potentially top players.
"You can only judge them by the level of their improvement over the next few years.
"We know about their temperament — we certainly know about Welbeck and Macheda.
"Obertan has only just started at the club. He's had a long spell out with injury but the signs are good with him.
"The one thing we can't give them is experience, which is why they played in the match with Besiktas.
"Hopefully that will bring them on."