Based on a note from Admissions (and numerous past points regarding the process), USMMA has basically extended all appointments that it plans to extend. Sure, the normal caveats remain -- if they have too many turn down by May 1, then they may offer appointments to a few on the Hold list.
But, generally speaking, they have already offered a full slate of appointments assuming that some percent would decline, (I think for the class of 2017 it was approximately 68% or so). So, if their goal was to fill a class size of 250, then they extended approx 367 appointments (for you math whizzes -- 250 divided by 0.68) to achieve the desired acceptance number. Kids have been accepting appoints for months -- so I doubt that there is much uncertainty any longer in the Admissions office.
Furthermore, since the big 3 SA's have been slightly reducing class size, (other posts suggested USAFA was the first to do so last year, with USMA and USNA following suit this year going from 4400 mids/cadets in the brigade to an eventual number of around 4000 in a few years), then this would convince many on the admissions bubble with these schools to accept perhaps a 2nd choice (which in a few cases is KP). With only a 250 class size, then it doesn't take many with a KP 2nd choice to take slots that in past years might have normally gone to Hold candidates.
My opinion only, but given the slight size reduction of the big SA's, I think it's possible that the USMMA acceptance rate might actually increase this year -- thereby yielding the number of candidates showing up for induction to be greater than 250.
But, all that aside, kids who are still "Hold" candidates, including my DS, need to move on and work on the next best alternative. I suspect that most of these kids, given their nature, work ethic, accomplishments, etc would have pretty good 2nd choices, anyway. So, the key now is to move on. And, since we are starting to run out of April with the May 1 deposit deadline for most schools quickly approaching -- they need to move on expeditiously.
If KP calls in the meantime, great. But, the chances are pretty low.