Read the last two paragraphs of the article:
So hold on to your wallet. Congress has many options when it comes to tapping this vast reservoir. It could eliminate the deduction altogether or just for top earners, further restrict the amount that is deductible (currently $17,500; for those over 50, $23,000), start taxing retirement savings growth, or take back the part that has grown tax-free.
In the throes of a retirement savings crisis, none of these options is appealing. But that last one is most troublesome. At stake is any savings that has accrued tax-free in a Roth IRA. Tax-deferred growth could be a target too if you find yourself in a lower tax bracket in retirement. There is no discernible momentum behind such measures. But a retroactive tax on this sheltered income has been a worry from the start. And now these accounts have a meaningful totaland everything is on the table.
However, as I've posted elsewhere, I don't think Congress will touch prior contributions. The worst they could do without setting off a panic sell-off is change the rules for future contributions.
And I hope you also noticed another sentence in the last paragraph. I'm going to make it as obvious as possible for all the Chicken Little's:
Wouldn't a retroactive tax on 20 years of 401(k) savings be an ex post facto law?
-PJ