Has it ever been made public exactly far ahead of his family August would have been when he disappeared? OK, it cannot be truly exact since no one ever saw him again after he took off, but, say, how long thereafter did his brother and parents, respectively (IIRC, August took off first, followed by the brother, with the parents trailing some distance behind), get to the planned meeting place? Was it more like just a couple of minutes, or more like ten or fifteen? If it was just a couple of minutes, I don't think it's very likely that he was taken/kidnapped, but if it was ten or fifteen minutes before anyone else got to the top, then that type of scenario would have been more feasible.
I have, however, believed from the very beginning that whatever the cause (most likely accidental, but he could have gotten lost, or even committed suicide

), August is still in close vicinity of where the family was that day.
If he was taken for financial or political gain, there would most likely have been a ransom demand (unless, though unlikely, there has been one, but the family and/or LE cannot disclose). It could have been a case of robbery gone wrong, too, but, in my opinion, that's the least likely scenario.
Whatever the case, I truly hope that his family will know the truth (I think not knowing is the worst) in the near future. This is a parent's worst nightmare.