I think, especially when it comes down to USAFA and USNA filling out the final class size, it can take a while to get the final appointments out. If you take a look at the self-reported appointments for c/o 2023, you'll see that there was a big wave of appointments on April 17, one day before TWE's went out. You're never out of the running until you receive that letter, and even then, there are stories of people receiving appointments despite having been handed a TWE. The point is, DS isn't out of the running until I-Day.
Definitely begin to consider Plan B, C, etc. as the days tick on. Start looking at the logistics of attending civilian college. Don't put all of your eggs in one basket, because it's never good to miss the housing deposit deadline for a university.
It's never over until it's over. Patience is key with Service Academies. Don't throw in the towel, because that BFE might come after all. Good luck to you and DS!