I mean, suppose a significant Earthshake damages part of the Great Wall beyond repair or something? I mean, where they now WOULD, maybe not to the extent of those in the Mysterious Beyond, have to fear Sharpteeth attacks 24/7? I mean, the Great Valley itself isn't even foolproof (Note Sharpteeth near Saurus Rock, though maybe that's why they were killed.)
BTW, even if nothing like this does happen, does the Great Valley have any "defenses breached" drills or something? (I mean, it took them a while to find out Chomper's parents had gotten into the Great Valley. On the flip side, they were on to Red Claw a lot faster, perhaps because THIS time, the kids had mentioned the breach BEFORE the Sharpteeth had gotten in too far.)
While only two to three Sharpteeth have even been seen getting in, what if someday like 20 or more got in? The security isn't foolproof also if Ozzy and Strut were, as far as we know, NEVER noticed by the adults.
Heck, that's another thing, what if a GROUP of Egg Stealers got in and decided to go for a nighttime nest raid?
Also, considering how bad racism is in the Mysterious Beyond, how do they keep different species among the Far Walkers from fighting each other when they come to the Great Valley?
They do seem to have plans for fire, floods, and hurricanes, and seem to have some ability to handle droughts, but what about Sharpteeth, Egg Stealers, volcanic eruptions, or domestic insurrections or disputes (with how easily the grownups argue in LBT, it's a wonder one hasn't happened yet!

)