Isolate the over 50s?
Well that means our GP practice of 11 doctors would be down to 5 - so that wouldn't work.
My DS's school would be in a similar position with the teachers and admin staff (including me).
DH and I are over 50 and still have a mortgage. I'm very happy for the tax paying under 50s to pay it off and I can take very early retirement - but I doubt that'll happen.
Many managers, CEOs, business owners are over 50. That means they close their businesses? And the under 50s who work for them do what? Go on the dole?
And, as people like Martin Lewis always tell you, the final few years of your working life is when your pension contributions ramp up in your little pot. The government would have to find a way of ensuring pensions were still at an appropriate level for people 17 years down the road - assuming retirement is at the current age of 67. I doubt the under 50s could manage that.
Otherwise, as well as taxes rising to nurse the economy back to its feet, taxes will go up to support a huge number of working age people for a number of years before they retire. Wouldn't work.
Plus, of course, you lose a huge range of experience if you put all the 50 plus people out to pasture.