So I don't think that will be a big factor, though the money into a taxable would be.
It's perhaps important to realize that none of this RMD "simplification" will be a big factor.
According to the
budget's numbers (p.124), this particular proposal is expected to reduce the deficit by a
total of $5M in its first 5 years (for some reason it's actually projected to
increase the deficit slightly in its first few years, but then the yearly decreases start getting larger). In comparison, the proposal to allow long-time part-time workers into 401(k)s is expected to increase the deficit by $253M over 5 years, and the proposal to allow penalty-free withdrawals for the long-term unemployed is expected to increase the deficit by $1.1B over 5 years.
So that $5M is essentially "nothing", which leads me to believe this is a rare case of political honesty, and the reason for the proposal
is actually just to "simplify" the rules between IRAs, rather than to generate revenue. And conversely, since the "benefit" to the government isn't that great, that means the "cost" to investors must not also be that great.