But mid level encroachment is literally in that field
My answer was mostly tongue in cheek but I'll address your concern.
1. Mid level encroachment is happening in just about every medical field outside of surgery, but even then NPs are often utilized in surgical clinics and in ORs to assist surgeons with cloasing etc. So anesthesia is not alone. And with the all out push by the nursing association for greater independence of NPs, (in FM, psych, IM) this is bound to get worse before it gets better. The VA already allows for APRNs to practice independently without physician oversight.
2. A field's stability can always change apart from midlevel encroachment. Look at CT surgery and Neurosurgery. With the advent of interventional radiology and cardiology, the need for aneurysm clippings and CABGs have decreased. CT surgery was once a hot field, now look at it. A lot of CT surgeons are fighting to find patients. Why get cut when you can get a stent or PCI?
3. People have been bitching about CRNAs in Anesthesia and how the field is dying since the 1980s and us MDs still here. Jobs are still frequently available if you're willing to move and you still get paid quite well.
4. If you talk to a majority of CRNAs they don't want to practice independently because they don't want to deal with the liability or pay for malpractice coverage (though they still do have to get it) and most understand their limitations and gaps in knowledge. Only the vocal few in the AANA keep bringing this up.
5. No one can predict the future and at this premed level, it's silly to even consider this as you'll never know what you're going to end up doing let alone how that field will be 10-15 years down the line.