But is it really a good idea to change the way we ask about race when things appear not to be backwards compatible?
The current way we ask about race/ethnicity is completely idiotic and is completely counter-intuitive to how regular people think about the subject. No reason to be tethered to something that isn't working just because the transition might be difficult.
The transition will be easy. It's just a matter of asking the race/Hispanic questions in a different way. Very few people will remember how they answered the 2010 Census.
The backwards compatibility problem is that you won't be able to directly compare the 2020 results with the 2010, 2000, 1990 or 1980 data because the questions were asked in a different way. The Other race population is very likely to go down, with little way of knowing exactly why, especially if they add a separate category for Middle Easterners and North Africans. I suppose that's more of an issue for historians than anyone else.
I don't remember - did they ask for Middle Eastern ancestry in the 2010 census itself, or is our ancestry data solely from the ACS data?