[Dylan16807]

The price only reflects the future value out so far. The market price is based on a small number of decades. So for the purpose of respecting the discount, that reason dries up after a while.

[_heimdall]

Stipulating that such contract must expire after a period of time seems more reasonable than saying such a contract isn't valid at all.

[triceratops]

So add a time-limit to the restriction.