Even in unplanned inner areas, you cannot do whatever you want. For example, not three bungalows instead of one house. That could, for instance, mean 9 parking spaces. And development plans can also be created. Demolishing and then hoping that in 15 years you can build however you want – or what would be possible today – is very optimistic. I would probably demolish and build a small two-family house with the option to revert to a single-family house.