Equal in quantity? So if the number of <18yos is X and there are X people over the age of 90 then that's the cut off, but if the following election there were f

Equal in quantity? So if the number of <18yos is X and there are X people over the age of 90 then that's the cut off, but if the following election there were far fewer old people then there might now be X over 70s so the cutoff gets redrawn there? Seems quite awkward operationally even if everyone agrees with the principle behind it. And even if you agree that it's problematic when older voters sway decisions that will affect future generations more than them, does matching the number of non-voters at each end of the spectrum solve that? And does the solution bring more benefits than the negatives of losing the experience of those old people + the negative of stripping a huge group of current voters of their voting rights?