make that a 100 years easily. (atleast in my country).
Heck, some houses don't even have architectural drawings because of their age.
As long as the roof and exterior walls hold up, there's not much to it. And the roof you change every dozen years or so.
You can find plenty of poorly constructed 100+ year old homes in the US, with original innards put together every which way in a shoddy fashion before there were building codes and standardization of construction. And yet there they are, still going with basic maintenance.
I live in Denver. Houses last way longer than 50 years here. Old houses here are quite desirable due to many of these neighborhoods proximity to downtown. The last two houses I rented were from the 1929 and 1943. They were in great shape. They were not the "old house" on the block either, both neighborhoods dated to that era.
Of course they have had several roofs in that time, but roofs don't last much longer than 15-20 years here due to hail. Siding has a limited life, but Hardie Plank which most new builds I see around here has a very long life. Brick will last basically forever along with plaster walls and hard wood floors. The foundation, framing, and plywood basically last forever if you keep it dry.
I have asphalt roll roofing which is cheap but needs to be replaced every 5-8 years.
Even if the home is habitable there are other reasons they are removed. After a certain point it makes more sense financially to tear a home down and rebuild than to continue to renovate it. Also markets change over time, and homes are not always built in a way that maximizes the use of the land. An area that was mostly bungalows and ranches can have homes replaced with larger homes or multifamily buildings.
A house should last 150 years at least, provided it's maintained.