A version of what you suggest has been the law since ERISA was passed in 1974.
The problem is what to do if investment performance doesn’t meet expectations, lifespan increases, or future assumed yield decreases. Generally companies had to pay enough to be back to even within seven years. Newspapers sought the right to have thirty years to fully fund. McClatchy was larger than Congress was comfortable with and found itself unable to pay the required fraction of the difference between the NPV and finding amount. Hence, it declared bankruptcy.
The problem is what to do if investment performance doesn’t meet expectations, lifespan increases, or future assumed yield decreases. Generally companies had to pay enough to be back to even within seven years. Newspapers sought the right to have thirty years to fully fund. McClatchy was larger than Congress was comfortable with and found itself unable to pay the required fraction of the difference between the NPV and finding amount. Hence, it declared bankruptcy.