European Cup winner Stepney believes the goalkeeper's jersey is now De Gea's to lose.
"Unless David makes a huge mistake like he did against Fulham, I think he will keep his place and be the permanent keeper in the Premier League for United," Stepney told the Manchester Evening News."That's the way it looks like it is panning out. The manager has said he's a shot-stopper and a line keeper and that seems to be accepted now.
"When he comes for the ball he punches it virtually every time and United appear to have come to terms with that.
"That's his style and as long as he does it well we shouldn't complain. Personally, I would still prefer to see a goalkeeper command his six-yard area, win the ball in the air and hold onto it.
"A keeper has to be in charge of that area and dominate it with a safe pair of hands. That's how Peter Schmeichel and Edwin van der Sar did it.
"But I understand that you may never get a keeper like that for another 10 or 15 years. They don't come along every day of the week.
"I remember David's display at Norwich earlier this year and I thought it was strong and powerful. He was coming for balls, collecting them and looked like he was getting to grips with the British style and the demands of the Premier League.
"I hoped it would be a turning point in his game in terms of how he kept goal but he's still a puncher.
"However, the defence now knows that when David de Gea comes for the ball he is going to get a fist on it and they know he'll deal with it in his own way. So long as he does there isn't a problem."