England boss Roy Hodgson believes his young side "can get better" ahead of the 2016 European Championship.
"We know that in France we'll have to be every bit as good as this, if not better," he told BBC Radio 5 live.
"We can get better, not least because so many players are so young."
Hodgson added: "By France 2016 they will have so many more football matches under their belts."
Wayne Rooney moved to within three goals of Sir Bobby Charlton's all-time England record of 49 as he scored twice at Celtic Park, with Alex Oxlade-Chamberlain opening the scoring.
Andrew Robertson scored his first international goal in the 83rd minute to give Scotland hope but that was extinguished by Rooney's second two minutes later.
Hodgson said: "It's not just the goals with Wayne Rooney, is it? It's his work-rate, his understanding of what we're trying to do, it's his influence on the field. But I must also mention Danny Welbeck - I thought he was equally as good.
"With those two at the moment we have an interesting duo and a potent attacking force, made even more potent when Daniel Sturridge comes back from injury."
Hodgson fielded a relatively inexperienced international side, with Southampton duo Fraser Forster and Nathaniel Clyne, Manchester United's Luke Shaw and Arsenal's Alex Oxlade-Chamberlain all starting.
"I think my team really enjoyed the atmosphere. Both sets of fans were incredible, and ours made so much noise in the game," added Hodgson. "We established control and I thought there were very few periods in the game where we didn't have full control.
"That performance is right up there. There were times today when we worked high up the field and there was some really good combination and attacking play, and every time we lost the ball we won it back so quickly.
"There was some incredible effort there. And defensively we were very solid."
Scotland manager Gordon Strachan felt his side let themselves down in the defeat at Celtic Park.
"That's as good as I've seen England play in a while; maybe we were mentally fatigued from Friday," Strachan said.
Hodgson added he did not hear anti-IRA songs sung by the travelling support.
He said: "I certainly don't have any comments to make about it, I certainly didn't hear anything."