Affordable housing is the only type of housing that will ever be built. Builders aren't so stupid as to build products that their customers can't buy. Government intervention is not needed.
I'm not sure if you're intentionally changing the definition of "affordable housing" in an attempt to make the desire for it seem silly or if you genuinely don't know how the term is typically used. But what you're describing is generally referred to as "market-rate housing" and not "affordable housing".
I like this reasoning. If there exists a person or organization that can afford to buy a thing then it is an affordable thing. Now this might sound like a tautology but that’s only because it is
Just up the street from me, a local builder is trying a tactic I have not seen before (in our area, at least). They are building out a new neighborhood, but it is quite diverse -- one end is dominated by duplexes in the 500K range and some smaller single family homes. The other end has larger, nicer homes priced at 2M or a little over. All in the span of a quarter mile or so.
They think it will work. I will be interested to see how it plays out.