Remember that the prices were set so high to prevent housing plot sales. It wasn't to make them affordable after months of gameplay, but months of gameplay beyond the 4 months (or for Legacy, beyond the over the 2 years) already played.

Internally SE knows how many houses their current capacity can handle. It's probably more than 5 per world (or whatever the current sales number is), but is likely less than a small number like 30.

Friday Legacy housing prices drop by 12.5%, the second of many steps of the "Legacy World price plummet" program, but later in January prices across all worlds will be "re-evaluated". This is where we will see how much SE wants more sales. The few sold may make them lower pricing significantly, though they also don't want a rush of purchases that will overload capacity.