Barkley, Sterling, Shaw, Stones, and Ox are the best English talents (of their age) and i think that they will be nailed on to be in future England squads. I actually think that Stones is possibly the only one who'd miss out on the First XI but that would depend on how Jones/Smalling develop.
In regards to Barkley he really does look like he has the potential to be a 'complete' midfielder so to speak. He's strong, he's got a cracking shot, he has pace, he has drive and determination, he has good technical ability, he can dictate the play, he can spray passes...he's just a joy to watch. The only thing stopping him at the moment at times is naivety, but he's a determined lad and Martinez is the perfect bloke to ease that out of him i think.