You aren't giving balances here, or expenses. So, this is a general answer. Keep up the pre-tax contributions, because when you hit pre-59 FIRE, living on savings and taxable investments, you are in an interesting place, tax-wise.
If you are really going to live mainly off his taxable brokerage for a while, those will largely be long-term capital gains, and the tax rate for MFJ is 0%, up to $89,250. If you are going to make $15-$20k on the side, this is "counted" first. But, you also get, at least, your standard deductible. So, if you are withdrawing less than $89k or so from the brokerage to live, you have some space to do roth conversions in the 10% or 12% bracket.
The full story is more complicated than that, of course. If you are on an ACA health insurance plan, you don't want to torpedo your subsidies with Roths, or you could spoil the math. In my case, we have an 8 year old, so also have some nonrefundable credits to throw into the calculation. But in my 3 years of FIRE as a real example, I'm able to convert about $40k per year, without writing a substantial (> $100) check to Uncle Sam.