That's an example that hits close to home as 2 close family members are Nurse Practitioners. This is a flawed example because Registered Nurses do not do the same job as a physician and are legally not allowed to learn how to do it. What if the nurses were allowed to shadow the physicians for 4 years? That would be called residency.

What if you have Nurse Practitioners with a Nursing BS, 4 years of nursing experience, a Masters degree in NP, and 4 years of experience diagnosing, managing complex conditions, etc.?

I personally know of several examples of Nurse Practitioners who are a drop-in replacement for an MD and that was achieved through work experience.

Just to remove any doubt, I have a lot of respect for nurses.

But the question was more about, say, should we close now all the MD schools and replace them by the alternative path you describe?

Nurse practitioners are allowed to prescribe and see patients without a medical doctor in some states, you might not be far off...