Can you elaborate on what newer tech would make older homes worth less?
Insulation. In the UK an older £250k house could have £2k additional heating for equivalent comfort. Over decades that adds up. If climate change makes summers hotter so cooling systems/AC need retrofitted and winters colder, that'll be more pressing.
Modular factory built homes might be possible to disassemble or extend, allowing reconfiguration that people might come to demand.
This will also be pushed by other trends, aging populations mean people might demand more housing that better suits their needs and new is cheaper than adapting.