If Mr Hollande wins in May (and his party wins again at legislative elections in June), he may find he has weeks, not years, before investors start to flee France's bond market.
His argument is fairly straightforward: packing cities in tightly creates economic growth, but people flee these wealthy urban regions because regulations have strangled market checks on housing prices.
In the event that we do begin to see more concerns over defaults in the Municipal bond market, we will start to see investors flee municipal bonds, putting tremendous pressure on prices.
In this respect, we need to heed one of the lessons of this Hall: it will do no good to tightly regulate a market only to see the bulk of activity flee beyond our reach.