Barkley's issue is he's completely and painfully inconsistent. One game he scores a cracker from 25 yards and wins tackle after tackle, another he refuses to pass, holds on to the ball for ages before losing it and sucks defensively. The thing holding Barkley back from being a potentially great player is consistency, he's all over the place, for an international tournament inconsistency is a big problem.
Vardy is in disgusting form, way way better than Lallana, his finishing and movement is great but his work rate is insane. He'll close people better, win the ball more, pressure the opposition into errors, latch onto loose balls and help create chances all better than any other wide players we have by a mile.
I think one of the biggest things to do is find a replacement for Henderson, I can't remember which site said it but in summing up his performance they stated he seamlessly took over for Rooney in randomly screaming at other players for not doing something he himself wasn't doing either. There is something about having a guy like Rooney on the pitch being captain screaming at other players for a bad pass, shot, tackle or decision.... when he himself is the worst player on the pitch almost every game.
If we manage to not take Rooney, AOC or Walcott in the team, I don't think England would win but I think it would give better players a chance to have a tournament playing with the right players, the right mentality and start to build a team together for the future.
Rooney's presence probably off the pitch as well as on it, is bad, Walcott's attitude is dire and shouldn't be near the team and his ability on the pitch doesn't deserve to be anywhere near it. AOC... a player who actually makes Walcott look talented.