Every month, your employer transfers Bitcoins into a time-locked address that can't be transferred out before you reach retirement age. You have the key to the address. You can verify the transfer on the blockchain.
No middle-men. No funny business. No brokers with pyramid/eyeball shaped logos. No "oops we went bankrupt and lost your retirement." No bail-ins. No raising the age of retirement.
Just Bitcoin.
If your boss is running a blockchain company, why not? But the question is what would the token/coin's worth in the future when it's time? By this time let's say that you already have a thousand dollars worth of token, but what would be the price of it after several years?
So why not deposit fiat money instead?