The test scores and grades are among the primary items used as a barrier to entry, so I wouldn't bet on that. The Court's primary objection seems to be the apparent existence of racial quotas, based on how much time Roberts spends talking about the tight demographic bands Harvard adhered to during the time period in question. Universities could probably fight this with statistical models, where they identified students who outperform the scores we would expect to observe. They could use diversity factors they're allowed to consider like parents' income, the student's school's relative test score performance and what not. We know good and darned well that racial factors tend to predict the baselines, on those.
Roberts came out swinging about that sort of approach, but I have a hard time seeing it stick if the response is sophisticated. I think he would fight something like a geographic approach as thinly-veiled. I think we will learn something about just how committed Harvard (and others) are to need-blind. If they want to keep those numbers looking the way they currently do under this decision, they will probably end up pulling a lot more from rural America and urban blight than at present.
It's worth pointing out that if you look at the demographics, Asian-American students are the one demographic that is already overrepresented by a huge margin (factor of three) at Harvard. That comes primarily at the expense of Hispanics, and to a much lesser degree at the expense of African-Americans. The proportion of White students is more or less exactly the proportion nationally. A cynical way to look at the decision is that the Court found for Asian-Americans saying that they should get an even larger share, at the expense of the socio-economically disadvantaged, given current admissions criteria.
The implication is that the present selection process may not be the best, if we value diversity and the meritocracy of talent. Roberts raises some valid points, but he has a little more faith in the values of the institutions than I probably would have. I think the big universities can beat this, but it will come at a financial cost. Will they pay it? If so, I would not be surprised to see Asian-Americans get shafted by this decision in the end.