The law is not settled. It has been misinterpreted.
“Every Person born within the limits of the United States, and subject to their jurisdiction, is by virtue of natural law and national law a citizen of the United States. This will not, of course, include persons born in the United States who are foreigners, aliens, who belong to the families of ambassadors or foreign ministers accredited to the Government of the United States, but will include every other class of persons.”
Senator Jacob Howard,
co-author of the citizenship clause of the 14th Amendment, 1866.
You need to look up the definition of "settled law". Ark was decided well over 100 years ago, and has been affirmed in a number of subsequent decisions and has never had any substantive challenge against it. Nothing could be more reflective of settled law more than Ark.
I have to laugh at people who say one thing, and then say - Hey, but that's not what I meant. Whatever it is Jacob Howard argued he meant when he co-authored the 14th, what the 14th actually says is plainly clear, or so has held in EVERY federal court that has looked at it.
As Gray spells out in painstaking detail, "subject to the jurisdiction thereof" had a specific import at the time it was used in the 14th, and that import included "aliens" who were not diplomats or members of an foreign enemy army under arms.
I'm familiar with the Howard quote that you reference. It's excerpted from the Congressional Record during the debates on the 14th Amendment. I would recommend that if you're really interested, you should read the entire Congressional record during the debate. From those records, it's clear that whatever Howard intended, the contemporary opponents of the 14th (and there were many) knew full well what the practical application and result of the 14th's language "subject to the jurisdiction thereof" would be. The opponents knew that language would specifically allow alien children born in the US (not of diplomats) to be US Citizens at birth.
Those records (which are now called the Congressional Record) were cataloged in a publication called The Congressional Globe. They may be found starting here. You can see from the text that PA Senator Cowan is taking tremendous issue with the proposed Amendment because he knows full-well that it will extend citizenship to all children born in America (save for diplomats) irrespective of the status of their parents. He even uses the phrase "commit trespass" when referring to the Gypsies that plague his own state. Honestly, Cowan is remarkably prescient with with his predictions - every he envisioned has come to pass.
I'm all for changing the criteria for birthright citizenship, but I don't believe - despite some well-articulated scholarly arguments that I've read - it can be done without another Constitutional Amendment partially repealing or refining the 14th.