I do think there's truth to this. It's a big problem in the UK and a good illustration particularly as London has been the real source of economic growth for the country as a whole thereby resulting in that concentration you mention.

This talks about it a little without fully committing to the actual problem https://blog.lgim.com/categories/investment-strategy/why-lon...

Seems to me remote working and the improvement of "cheaper" areas, organically (as more people spend money in these areas and increase demand for services there) is the most viable solution but something governments can't seem to grasp or choose not to grasp