What is it with athletes in the 400 m, that never attempt to run both individual events? Shorter sprinters do the double, middle distance runners do the 800/1500, long distance runners to the 5000/10000, or 10000 and the marathon in some cases.
Warholm and Bol are generational talents, who could very well run them both. Especially since the heats are basically a training run for them. Granted the organizers will have to help with not scheduling both events in the same days.. And don't say it's a hard endurance race of.... 50 seconds, where if you run once in 2 days you are spent for the rest of the week. There are harder demanding sports, than the 400 m, like cross-country and biathlon where athletes are competing 3 consecutive days.
Yes, you need technique for the hurdles, which makes the option very limited to pure flat sprinters. But the hurdle specialists like Warholm and Bol souldn't have issues attempting both events, especially when they have top results in both of them.