I'll make a Boling prediction:
If you look at the US Olympic Trials there is a good 3 day break between the final of the 400m and the opening round of the 200m. It would make sense for him to enter the 200m as well as the 400m just in case something goes wrong in the 400 - he would then still have the opportunity to make the team via the 200. Boling, however, does not currently have an automatic qualifying time of 20.30 for the 200 and his best legal time in the qualifying window is a 20.52. There's no guarantee that time will make the field. Look for him to run a 200m race in the next two weeks. If conditions are good and he's just recently started up his speed training phase, then I predict he PRs in the 200m.
If he does that he'll go into the 400m trials strong, fast, and confident. I think he'll have a decent shot of making one of the three individual spots and definitely will make the final 6 which will justify him getting to at least run the preliminary heat in the men's 4x400m as well as the mixed relay. I'll predict he comes away from the Olympics with two gold medals and an outside shot of possibly winning an individual. I think there is also a good chance that after the Olympics he could PR in the 100m as well.