Not to worry, GM's pension is covered by the PBGC (i.e., the taxpayers) if GM is unable to pay.
PBGC only covers pensions up to 28k per year, far less than the current GM pensions.
Both my parents are GM employees who are counting down the days until the pension kicks in. They never had to save a dime for retirement and even make fun of me because I work for a small company have to save my 10% from every check.
Thing is that what goes around comes around. With these defined bebefit plans if you die its not your money to give to your survivors. With your own saved pension plan the money is yours to keep.