All of these are entirely possible, BUT with a population of vultures, plus ravens and other corvids, in the park their bodies should have been attracting a lot of attention.
https://www.nps.gov/jotr/learn/nature/birds.htm
From what I've read, 2 adults
should be able to drive off a mountain lion. In addition to which Joseph was reported to carry a knife when hiking. Could a mountain lion drag away an adult? Rachel maybe, but what about Joseph?
Caves? Maybe. It would make sense for them to take shelter in a cave if they were in trouble. However I'd expect the searchers to know the locations of all of them and to have checked them all by now.
Dunno. It doesn't seem to make sense. If they simply got lost,
all of their experience and training seems to have gone out of the window.
I asked this a day or two ago but nobody answered - do we know what they were wearing when they set off that morning?