Correct me if I'm wrong, but Medicare-for-All is just public insurance. It's not a state take over of all private hospitals.
But instead of negotiating a price with you, the hospital will be negotiating with the state. Hospitals can still compete on prices and likely the state will grant contracts for non-urgent services to the cheapest provider..
Modulo, whatever level of free choice is left and what capacity is available, etc..
Disclaimer: In full support of single payer/government managed healthcare
It's not like there is any competition right now? You can't even get a price quote for elective surgery.
Also I wouldn't be so sure that your children don't have significant leverage over you, hehe :) (They probably don't realize how much leverage they have)