Looking at the IAAF simulations for 2019 (see link below), it looks like the U.S. would have had at least 7 Olympic qualifiers in every middle distance and distance event except the men's and women's 10000 meters. For some reason, the U.S. is relatively weak in the 10000.
People keep citing Chelimo's silver medal in the Olympic 5000m. They say he would not have gone to the Olympics because he did not meet the qualifying time. But Chelimo probably would have qualified based on his prior experience in the event.
I think people are overly focused on the qualifying times, which are very fast, rather than on the IAAF's ranking system, which allows much slower runners to gain entry.
In the marathon, which seems to be the focus of much angst, nearly two dozen American men and about two dozen women would have met the new IAAF qualifying standard, according to the IAAF's simulations.
Of course, it is possible that an up-and-comer will place in the top three at the trials next year and not qualify for the Olympics due to his or her lack of a fast time and lack of points in the IAAF standings. I can understand the frustration this will produce. However, I believe similar situations have occurred before many times in the past. Fans and athletes generally understand that finishing in the top three at the U.S. trials does not guarantee an athlete a spot in the Olympics.
Also, maybe it is not the end of the world if a flash-in-the-pan runner like Charles Jock is replaced by a 4th place trials finisher who has a better track record. It is not written in stone that the top three finishers at the trials are necessarily America's best three athletes. Nor is it written in stone that choosing the top three finishers at the trials and disregarding every other race is the fairest system. It is at least conceivable that the new system will result in better athletes and thus will increase America's competitiveness at the Olympics.
If athletes want to compete in the Olympics, they will know in advance that they must fulfill the Olympics qualifying criteria, and they will conduct themselves accordingly. That means either accumulating points in the IAAF's ranking system or running very fast.
While the new standards admittedly are quite different from the old ones, I predict that the practical effects will be relatively small. The vast majority of athletes who are capable of finishing in the top three at the U.S. trials will be among those who have met the Olympic qualifying criteria.
The primary exceptions will be (1) people who were unable to compete in the prior year due to injury and (2) people who are trying out a new event. For example, if Shelby Houlihan decides to run the 10000m in the Tokyo Olympics, she had better compete in the 10000m this year, or else plan to run really fast in the 10000m in the spring of 2020. It won't be enough simply to finish in the top three at the trials. Then again, I assume Houlihan would have to run at least one 10000m even under the old rules in order to qualify for the trials.
The IAAF simulations are here: https://docs.google.com/spreadsheets/d/1xLvY8fR7TmiKPmK67cRkt7bmk36QpbdcyyW_JWK7Ko4/edit#gid=1450965003