Is the labor market tight enough for the signaling requirements to relax naturally? If employers struggle to hire enough entry level people who can read memos and learn basic office software, they probably won't require a generic 4 year degree. But as long as there's enough labor that employers can still be picky, I don't see why/how employers will drop that easy (if blunt) 4 year degree filtering mechanism.

The signaling value of a traditional degree will go up if fewer people acquire it, so the optimal outcome for parents anxious about their own children's future prospects is that other people's children should consider vocational education or go straight from high school into the work force.

I say this aware that many high school grads without academic inclinations are nudged toward universities by default, to their irritation and to the detriment of their more seriously academic classmates. I don't see how to fix it until/unless the labor market gets tight enough to squeak. Until then, every small move to fix the problem will raise the reward for "defecting" back toward earning a degree as a signal.