I've given up on being able to predict future tax rates. Frankly, I'm surprised they are as "low" now as they are. 2026 is still 3 years away, and the projected change is pretty small. Rates could go up, or down, or stay the same. And, it could happen in 2026, or before, or after. Who knows?
So for now I do Roth conversions based on the tax rates and brackets in effect this year. I expect tax rates will probably increase, but I could be wrong, again.
We live pretty comfortably with withdrawals and spending in our current tax bracket. I top up our current tax bracket with Roth conversions every year. My current projection is RMD will leave us in the same tax bracket.
But tax brackets, and tax rates, can change at any time, and I have no control.
I do Roth conversions to try to smooth things out. I'm paying extra tax this year in an attempt to keep things smooth in the future. But I do those conversions based on current laws and balances. I do not project the future.
Edit: honestly if we, or I, or my spouse, or our kids, end up in a higher tax bracket, that is probably a good thing. It likely means we have more than enough.