If the goal is the minimize the capital outlay of a greenfield build, your model can be more efficient, depending on the geography covered. Basically you're assuming that the active electronics to make a ring are cheaper than building high count fiber back to a central point. There are geographies where that is both true, and not true. I'll give you the benefit of the doubt that you're model is cheaper for a majority of builds.
Agreed, there are definitely scenarios where home running everything makes sense.
On the other hand, I am not nearly as interested in minimizing the up front capital cost. It's an issue, sure, but I care much more about the total lifecycle cost. I'd rather spend 20% more up front to end up with 20-80% lower costs over 50 years. My argument is not that high count fiber back to a central location is cheaper in absolute, up front dollars, but that it's at worst a minimal amount more and will have neglegable additonal cost over a 40-80 year service life.
Here's the thing, over the time frame your describing you're probably going to have to look at more fiber runs just because of growth in areas that you didn't build for before. Even if you nail the total growth of homes and businesses in your area your chances of getting both the numbers right _and_ the locations are pretty slim. Also, you're going to have to replace gear no matter where it is core or nodes on a ring. Granted gear that lives in a CO can be less expensive but its not that much of a difference (~1% of gear costs). Having a ring topology is basically the best way we've come up with as of yet to hedge your bets, especially since you can extend your ring when you need.
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