Pre-mortem for a decision

Run a pre-mortem on my decision: let's imagine it has already failed, and find the reasons ahead of time.

Decision or launch: [what I'm about to do]
Goal and deadline: [what I count as success and by what date]
Resources: [budget, time, who's involved]
What I already know about the risks: [if anything]

Do the following:
1. Imagine that [6 months] have passed and it all ended in failure. Write a "failure story" of 5 to 7 sentences.
2. Find 10 reasons for the failure, by category: customers and demand · product · money · time and team · outside factors (platforms, laws, competitors).
3. Rate each one: likelihood from 1 to 5 and damage from 1 to 5. Sort by the product of the two.
4. For the top 5: an early warning sign (what I'd see in the first 2 to 4 weeks), how to prevent it now, and a plan B if it happens.
5. What to change in the plan before I start: 3 changes at most.
6. One question I have to answer before starting.

Be tough: don't soften the risks and don't add encouraging phrases. The reasons must be specific to my situation. "Bad marketing" is not an answer.