Consumers' ecosystem: small flat - no stock

It is quite curious but completely logical: in big italian cities average flats are getting smaller and smaller (just tonight some friends of mine told me that in Milan a flat of 30 square meters costs 650€ per month), so people don’t buy more than what they consume in the short term.
Why not a “pay-today-take-when-you-have-enough-room-in-your-apartment” service?
Or should we think about eatable furniture?
Or should retailers help families to buy bigger apartments?