I don't think the 50 over format will be around for much longer. Not at World Cup level anyway. With a couple of notable exceptions most games are as dull as ditch water. As for England, Morgan and Plunkett were such important players (and captain) for us in the last world cup and they have never really been replaced. Albeit it was played in English conditions obviously.
The T20 will become 'the' world cup and played every two years.