The Supreme Court has blocked the Trump regime from adding a citizenship question to the 2020 census, but the ruling is only temporary.
The Court did not rule that a citizenship question would be unconstitutional, it only ruled that the Commerce Department can't add the question without presenting a good reason for it.
From the LA Times:
In a ruling by Chief Justice John G. Roberts, the court said the Trump administration did not adequately explain its reason for adding the question. "In these unusual circumstances, the district court was warranted in remanding to the agency and we affirm that disposition,” Roberts said. [...]
"Reasoned decision-making under the Administrative Procedure Act calls for an explanation for agency action. What was provided here was more of a distraction," Roberts said.
The Trump regime's failure in court mostly comes down to the behavior and actions of Commerce Secretary Wilbur Ross.
Trump has been gifted with the most conservative-friendly court in decades, but Ross has repeatedly lied about and misrepresented his reasons for adding the citizenship question to the 2020 census. And the court may have even overlooked his reasons, except Ross also did not follow proper procedure when adding the citizenship question.
The Trump regime could and I expect they will make another attempt to add a citizenship question to the census, but actually following proper procedure and applicable rule-making laws and clearing it through the courts will take a significant amount of time. It's unlikely that the question will appear on the next census.
What is likely is Ross's departure from the Trump regime in the relatively near future.