The day you are paid, you will still get handed exactly $100m million.
Every day between now and then you will still have exactly $100m in bond holdings. How many cheeseburgers you can buy with that number of dollars may change from day to day, but the number of dollars will not.
(Someone else is offering 100 future for 80 current because they have a forecast about cheeseburgers, sure. But you don't have to agree with that forecast to take their deal; the deal looks even better for you if you don't agree.)
Think of how you would report a non-transferable asset with maturation on your balance sheet?
How would you report savings in a CD with a steep early exit penalty?
Herein lies the difference between a list of assets, and a list of asset liquidation value.