King has struggled to make an impact at United since his arrival in 2008.
His only senior appearance for the Red Devils came as a substitute in a League Cup tie with Wolves in 2009, since when he has had spells on loan with Preston, Borussia Monchengladbach and Hull, with limited success, and it does seem his future lies away from Old Trafford.
The 20-year-old's international career has continued to develop though and the Oslo-born player scored his first Norway goal in their 3-1 World Cup qualifying win in Cyprus on Tuesday.
"Josh King has done very well," said Ferguson.
"We get mixed fortunes when players go on loan and Josh didn't play much at Monchengladbach last year.
"But he did well in pre-season and has been working really hard.
"He's shown he has good ability. He scored the third goal on Tuesday and that is bound to have given him a boost.
"He's very quick with a great physique and should have a good career."