Ironically, the banking industry would be devastated by inflation. Imagine what happens when you have even 2%-3% inflation after so many people have been refinancing 30-year mortgages at 4%-5% interest rates in the last couple of years.
You'd have to look at the average life of the bond.
People move, trade up, trade down, retire, die.....many things that cause their mortgages to be paid off in less than 30 years.