What is the biggest ticking time bomb in our society?

Young adults not being able to afford to save for pensions. This is often because property prices have risen by such an amount that it's impossible save for a deposit and save for the future. When my generation (I'm 33) begin to hit their 60s, there's going to be an almighty increase in poverty amongst the elderly. I'm writing from the UK, for what it's worth. Might be different elsewhere.