The issue with a lack of affordable rented accommodation in London goes back a long way. It seems to me that if the local councils had been given the receipts from council house sales in the 1980's and beyond to build more social housing we not have such a dearth of affordable rented accommodation in the capital.
Luckily FH still has a fair reservoir of social housing so I can't see gentrification driving out the key workers (in the broad sense not the narrow sense it is usually used in) just yet.