With that approach, the discussion would more look like "Our current cycle takes a full year to complete, let's reduce our projets' scopes by 10 to get down to a month or two at most"
That's even simpler, and you can even keep waterfalling and still benefit from shorter iterations.
It takes 6 months to act on customer feedback with our current release strategy, and a full year to fix the bugs related to that feedback. We should be rapidly iterating on feedback quickly to avoid churn. Let's try xyz...