Only Bangladesh and Ireland have made things interesting. And most likely they will be the No.9 and No.10th team for the next World Cup. Let the Associates play the T20 World Cup and then come into ODI's by qualification.
Canada, Holland and Kenya have done nothing more than provide warm ups for their opponents, maybe taking teams close and having some "magic moments", but they've not truly come close to beating any Test team.
Ireland beat England, that was a combination of good hitting by one batsman, and not great bowling - typifying England's World Cup. Other than that Ireland have yet to really fire.
Bangladesh beat Ireland and England, that means the ONLY Test team of the top eight to lose in this World Cup to a team outside of the top eight is England. That's hardly a conclusive argument for their retention.
My argument for their retention is that the sides won't improve unless they are integrated into some system that exposes them to better sides as well as sides of a similar standard. Once a side has become so clearly better than the rest, playing the rest won't help, they need a sterner test. It needs a tier system, for ODIs perhaps to start with, and then for Tests. Let Ireland, Holland and Kenya loose on Bangladesh and Zimbabwe, saves the latter two getting beaten easily so often while providing good contests. Top side in that tier gets promoted and see how they fare against the better nations, although I would advocate 6-7 teams to a tier so it is likely the side promoted would be on of the weakest sides of the top eight (probably England or maybe West Indies)
Part of me wants England to go out, they deserve to so far and will learn nothing if they progress. That said, they will no doubt learn nothing if they go out either, the words of Strauss and others suggest they think it is just bad luck, a below par performance or two, but it goes a lot deeper than that. The side lacks quality throughout. Those that are good enough are mostly not consistent enough, throw in 3-4 squad members who should never have been picked and you have a mix of inconsistency and poor quality which never wins more than the wooden spoon.
They picked three spinners, one is a batsman who wouldn't get a bowl but for the advent of T20, the other has barely a handful of ODIs to his name and hasn't got a game - even against the minnows! So that's the spin attack.
The batting is frail and prone to get itself out, not helped by the neverending quest for the holy grail of a keeper to open the innings. That has yet to work long term, so their alternate solution is open with Pietersen It's often a toss up whether the batsmen failed to get the 20-30 extra runs that might or would have made the difference, or the lacking of the bowlers that gifted extra runs to the batsmen.
Our supposed best attack bowler Anderson has long been inconsistent, this World Cup he has just been exposed. Bresnan isn't my favourite player, but he has done a decent job and Shahzad is learning, another whose lack of ODIs before the World Cup beggars belief and exposes poor/no planning.
Because there is no standout candidate for number seven, England have switched between batsman bowling the 5th bowler role, or loading the side up with players who are no great shakes with the bat and leaving a long tail. England don't make good use of the ODIs between World Cups, always looking ahead one series/game and not much further. They also have swung too far the opposite way against chopping and changing, so much so that ordinary players are given way too long to fail (Wright and Yardy) which they achieve a lot. If we thought Giles getting 50 Test caps was a joke, Wright and Yardy have eclipsed that - and some.