if 350-400 runs target becoming norm then everything is possible. and think what would happen if any team scoring 500 runs in ODI. finger cross if English batsmen come up against any weaker bowling side and every batsmen clicks on the same day then 500 target look easy very much possible target.
After watching the first warm up match India played i thought it is a bowling pitch and they have changed the pitch condition heading into the world cup, but the recent high scores confirmed that the Indian batsmen really played bad to get a below par score against New Zealand, with the batting power house West Indies, England and with Rohit Sharma firing even India can score 400 plus but 500 is an impossible task, if associate member teams were playing we could have seen 500 plus in these pitches 
.For Bold Part
Actually that Kennington Oval's pitch was seaming wicket in real, at least ball was doing tricks during the first inning. I posted about this yesterday in "World Cup discussion" thread. Quoting my post here to save some time
About the Last match between India vs New Zealand
I saw many fans saying that Indian batsmen performed very poorly which is 100% true, but everyone failed to see or avoid to mention that it was seaming-dark green wicket with the cloud over the head during the first inning — best condition for bowlers to bawl. Indian Captain Virat intentionally chose to bat first so that Indian batting can come under the microscope, and in this test, they failed miserably without any doubt. ( here I see Intent and awareness from Virat Kohli. which is a perfect sign for Indian Team)
And if seaming condition comes into play in the World cup, then every team going to struggle like that, not just India. Winning the toss is very important if it happens. And everybody knows, the Indian Bowling attack is no dummy as it used to be in the past.
