I hear things like "credits" for low-wage or no-wage employees or individuals, and a "reduction" in credits for employers to match over a certain income level. This could remove the benefit for employers to match 401k contributions, and remove any incentive for savers in 401ks.
“What he may do with 4012 plans”.....Biden has stated many times he will END THEM.
I suspect he will SEIZE them.