I believe that there will be some serious impacts on athletes from smaller countries or athletes who are not yet "rock stars" and have limited opportunities earn a ranking per say.
For example I have coached an athlete that qualified to compete in the Olympics, World Championships and the European Championships. In all three races they placed WAY higher than their qualifying time put them on the ranking list of qualifiers / entrants. Mainly because our focus was those championships, not world majors or chasing fast times, etc.
I hate to say this, but I don't think that the average person understands that you have to pick and choose your battles, especially in the marathon or longer events. You only have so many good dec / hep, marathons, 10,000m races in a person and if you spend them trying to move up some list then your performance at a championship (if you make it) probably won't be great. Championship racing is completely different than a Diamond League meet or a World Major marathon or flat, fast qualifying course. There are many other factors that determine success in the championship itself, in a marathon mainly specific preparation for a course, conditions, tactics, etc.. Qualifying times in marathons don't mean much.