It's a good question and one I have thought about myself a lot over the past year while working on materials about the Winter Olympics. I also started researching the Summer Olympics recently, too.
I've always thought Cricket should be included in the schedule. Now that there is a shorter, faster version of the game in the 20-20 format it would fit perfectly. It's also played widely enough for the level of competition to be even (it's this fact which the IOC often refers to when rejecting a sport - "It's not played by enough people around the world." or "the level of competition is not sufficiently high"). With cricket this is nonsense. There are at least 8 countries in with a chance of a medal (England/Britain, Australia, New Zealand, South Africa, India, Pakistan, Zimbabwe, Sri Lanka) plus numerous smaller countries that would willingly compete (Bangladesh, Kenya, Netherlands, Ireland, the various nations that make up the West Indies team). Any competition in the Olympics would only feature about eight to twelve teams anyway. Team sports are always organized like this. I'm also pretty sure they could find that number of teams for sports like netball and floorball.
I'll also add that if the concern is that the sport would be dominated by one or two teams, we need only look to Basketball and Ice Hockey for examples of this happening already. The USA, if it fields a strong side, would wipe the floor with just about every country in the world. Several others have strong-ish leagues but nowhere near on the level of the NBA. Similarly, the Soviet Union dominated Ice Hockey for decades. These days, Canada and the Czech Republic are equally as strong, but it's still a relatively low number. Most sports are dominated by one or two countries anyway (Britain: sailing and cycling, China: gymnastics and table tennis).
I'd argue for the removal of dressage, synchronized swimming, and rhythmic gymnastics. They are not sports. They are just dancing. Any sport that wouldn't work as a competitive event if you removed the judging should be cut (possible exception: gymnastics and ... grudgingly, figure skating). They are also just really crap and boring. Skating and gymnastics just about pass muster because they utilize and assess core athletic skills - skating, jumping, running - whereas synchronized swimming and rhythmic gymnastics are just too contrived. The former is simply a dance routine ... in water! Dancing is not on the program for a reason. Simply adding the water element doesn't make it any more of sport. Dressage sucks because the work is done by the horse. The 'athlete' doesn't do much other than call out commands. Their work is done before the contest.