I (sadly) predict worse than a punt. Our current birthright citizen policy is too baked-in for some of the squishier Court “conservatives” to try to overturn.
I sure hope I’m wrong.
I think birthright citizenship, as presently interpreted, is a horribly dumb idea. But I also think it is the most plain textual interpretation of the 14th. In other words, they screwed up when they passed that Amendment. But we're stuck with what it actually says, not what we think they may have meant or wanted.
I don't honestly think it involves squishiness at all. I thing you can have honest differences of opinion about what it means. Gorsuch, who is the most textual-oriented judge on the Court, will likely think Trump's order is invalid. Those who consider themselves more originalist than textualist may comes down differently.
sadly you are right. The punt is the best we can hope for.