This only helps if your demographic problems are far in the future, because you need to catch your workers when they are young enough to make this trade. In man

This only helps if your demographic problems are far in the future, because you need to catch your workers when they are young enough to make this trade. In many places, the cohort they are worried about is already too old for this to work. Also, I would totally expect people to game this system when they get older in order find ways to get out of that extra year or two of work that they promised. Expect a lot of 65 year olds to suddenly develop this or that disability that makes them unable to continue working.