I think 20k and 30k crowds is perfectly reasonable to expect for two unfancied teams. The percentage is largely irrelevant. The proper world cup would be the same for e.g. Jamaica v Japan held in the UK. The competition has to have representatives from each confederation otherwise it would be almost just European teams competing so this sort of match up is inevitable.
For me though, I don’t think anybody knows yet if this CWC is a good thing or not. There’s certainly concern from players and clubs about too many games, but there’s no way of making room for it because any reduction in CL or PL games will get voted down by clubs not in a position to qualify for the CWC (the vast majority). In the WC players want to represent their nations as a matter of honour and pride, especially when geopolitics comes into play, but that factor is completely missing from the CWC.
I’ve also mentioned previously about how the WC is a 2 year qualifying period and this generally ensures the better teams arrive at the tournament. Again the CWC fails with its 4 year qualification period, City being a perfect example. Our team had disintegrated from the point of qualifying to when the tournament arrived and we may suffer next season as a result. Whilst it created a few shocks by allowing unfancied but in-form teams to beat out-of-form bigger teams, it’s probably not going to make much of a difference to who the eventual winners are. In my view it should be a bi-annual tournament but smaller. I reckon when it is played again in 2029, it’ll still come as a surprise to most football fans. At this rate it’ll take 5 or 6 iterations to take off.
That’s if they can make it financially viable (i.e. not subsidised by a single nation).