I'm not sure if I share the same view of demographics as you.
People are living longer. As the 'baby boomers' die, they will be replaced by the next generation. Think about it. Most of those baby boomers will have children of their own. The UK population is now around 61.5 million and rising.
Look at this chart:
http://www.statistics.gov.uk/cci/nugget.asp?ID=6
You can see the baby boomers spike there around the 60 years old mark. But look further down too. By far the largest age group is around 35-50 years old - NOT baby boomers, but more like their children!. Given current life expectancy, most of those have a fair few years left in them yet.
Birth rates are currently on the rise too. Add increased immigration into the mix and I really don't see a sudden drop in the demand for housing on the horizon.