Assuming the company existed, and was not corrupt in handling all that money. But there is a lot of volatility in a company existing for 50+ years in the future, and there is a lot of corruption.

Hence the tightening of DB pension funding and investment rules (PPA 2006), culminating in non taxpayer funded DB pensions being untenable expensive.

401k funds are as guaranteed as any defined benefit pension. They both get invested into SP500 index funds, and they both get bailed out just the same by the federal government. If the stock market tanks, the DB pension is going down just like any 401k.