Regardless if job requirements change (they only will for a subset that no one cares about and no one is trying to get), you're going to screw people over. The lag time between no-loans and job-requirements dropping is going to be too long. There will be a lot of people who fall into the cracks and will be stuck with the lowest tier jobs because they couldn't afford a cash-only education until it was much less expensive.
Regardless of this - I feel like this is the wrong approach to debate lower costs vs no loans vs whatever-where-a-student-pays-in-the-end. I think 4 year college should be free (no tuition, books paid, stipend or special housing, etc.) given how the world works. I went to college for free due to CH 35 of the VA and it was really the only reason I was able to do it and fully commit to it. I have no problem with having a more educated populace - regardless of what they study. I did study something that came with very gainful employment but that wasn't obvious in the beginning of my studies. I think 4 year college would be less necessary if we had better education from the start - but we're never going to get there in this country.
If you want to limit the cost of college then doing it by putting caps on how much a university can charge could be a more straight forward option than hoping costs come down by limiting loans to those who can't afford the cash option. (e.g. If a university wants state funding then they need to cap their student costs) Even then - loans would still need to happen for people who can't afford much more than their basic housing expenses (if even that - think about kids who get kicked out at 18).
You're speaking in a lot of "if market forces behave the way we all think they should thanks to basic econ like supply and demand" but that's not how things always work in the real world.
Considering ~50% families don't have any retirement savings and don't have an emergency fund, do you really their kids are gonna be able to afford all the expense things associated with college? (Remember - these people just got out of high school! They have likely never had a job and have no money at all)