In terms of tea-leaf reading, I would characterize myself in the "this is not a great sign" camp. Alito, Thomas, and Gorsuch's votes are pretty well-assured at this point (not that any of them were really up for grabs to begin with). For the rest, the decision to maintain the injunction for those with close family connections could signal that the Court might try to do some fancy footwork on standing to knock out claims by John Q. Random Muslim while otherwise rejecting the ban as applied to those with a significant nexus to America. But maybe not.
On the merits (and I'll focus only on the constitutional issues rather than the INA claims), I've already written quite a bit about the efforts by some to act as if it's somehow unfair to use straightforward evidence of discriminatory intent to prove discriminatory intent (though I will also take this opportunity to link to this excellent post by Leah Litman, Helen Murillo, and Steve Vladeck). With Roberts and Kennedy as the swing vote, this becomes all the more pressing.
Over the years, we've seen a growing trend whereby many people -- including federal judges -- view discrimination claims as basically mean. By that, I'm saying that they view the claim "X law or Y decision unlawfully discriminates against me" as basically saying little more than "X or Y was done by assholes." At which point the listener thinks: "What a mean thing to say about someone else! How uncivil, to call them an asshole!" "Discrimination", as a concept, ceases to have analytical content which we look over and check against a particular fact pattern. Instead, it is taken as a sort of slur or insult, at the very least bad manners, which should rarely if ever be heard in polite society.
In conjunction with this, the federal judiciary has for years been pushing the burden of proof in discrimination claims towards a singularity where the only way to win such a case is when either (a) the provision specifically says it is targeting group X or (b) the person or organization responsible for the provision admits that it's goal is to target group X. This, conveniently, allows virtually all of those "mean" discrimination cases to be tossed out -- I mean, who could be stupid enough to admit that their goal is to explicitly target a particular outgroup?
Well, the President of the United States, apparently. And so we return to familiar ground: Sure, Donald Trump admitted that his purpose in passing the travel ban was discriminatory. But it's just so rude to act as if that's proof of some sort of illicit discriminatory motive! How could one, in Chief Justice Roberts famous words, "tar [him] with the brush of bigotry", just because his statements and actions give every reason to think that said "brush" is wholly and entirely warranted?
Anyway, I suspect that this will be the operative issue for Chief Justice Roberts and Justice Kennedy -- whether they'll be able to resist their deep, deep instinct that it's just impolite, just too uncivil, too gauche, to say that the President of the United States is a discriminator. My tone might illustrate why I'm in the "this is not a great sign" camp.
I'll say one final thing. If the Supreme Court does uphold the travel ban, I am quite confident as to the historical trajectory of the precedent:
- In 20 years, the case will stop being cited.
- In 40 years, the case will be viewed by the legal profession as an embarrassment; a naked capitulation to panicked racism and bigotry.
- In 60 years, the case will be denounced as an obvious mistake -- so obvious that it scarcely needs mentioning that we'd never, ever repeat it in today's enlightened age.
- And in 75 years, the courts will do it all over again.