A shortfall is information about this version of the idea. It is not a verdict on the whole hope.
Ask what kind of no it is
- Not yet: Would time, savings or debt reduction change the answer?
- Not this way: Is there a smaller, slower or differently structured version?
- Not now: Does another need honestly come first?
Change the scenario only when you have a real reason for the new assumption. Do not shave costs until the red number disappears.
Sometimes the answer remains no. Knowing that before making an irreversible move is one of the useful things a scenario can do.