401k (employer sponsored) and IRA (individual account) are managed by investment companies. They’re not a state operated asset. It seems unlikely that the government would move it away from these investment companies because they’re probably great a lobbying.

The law states that these retirement accounts should be completely untouched and recoverable if the company goes bankrupt.

Historically the market returns have been around 7% annually over the long long term but that fluctuates a lot and might not even be possible into the future but America is good at pumping those numbers up so idk.