I saw someone talking about the football world cup before, and comparing it to the cricket world cup, but now I can't find it to quote it, so I'll just post this here as it relates to the format.
The way I look at it is Cricket is very similar to Football/Soccer, but in a way it's also different.
If you look at both World Cups, in both of them there's only eight teams that are going to win it. In Football maybe ten.
The difference is in football much worse teams will always be much more competitive. E.g. a few days ago we saw like the 90th placed football team in England Crawley Town only lose 1 - 0 to Man Utd. If the 90th placed cricket team in England versed Somerset, they'd just get obliterated. Same goes with international cricket, in football the 50th placed tea, in the world can be competitive with the best, but they're still not going to win the world cup, while in Cricket India vs whoever the 50th placed team is is going to be a joke.
IMO the best way is to run the World Cup with only 10 teams (all vs all, then semis/final), but run the Champions Trophy knockout style cup with the minnows every two years. So maybe with the Champions Trophy you have 16 teams, 4 groups of 4, they all verse each other (so they play three group games), then quarters/semis/final.
That will provide a base for the lesser teams to get two/three top matches every two years, but also have a marque world cup without these matches which we had yesterday.
Also it will help bring the Champions Trophy back, as IIRC the interest in it was really down.
The World Cup would then have have 45 group matches, plus semis/final. If you play two group matches a day that's under a month, which will solve the length of it.
The Champions Trophy will have 24 group matches, plus quarters/semis/final, which would ensure that it's quick fire, but also serve plenty of purpose.