Do you really think that matters? I'm sure at some point they will. I don't think those members of Tribe Judah that have mixed with non Judah members will lose their heritage.
To claim an inheritance from deceased A, descendant B would first HAVE TO KNOW he WAS so descended, and that test is flunked.
I doubt it. The seed of Abraham is the seed of Abraham. I'm not aware lack of memory of that constitutes disenfranchisement. I'd be willing to look at the law claiming it.
I know what you mean of course, that when Elijah comes he will make these genealogies plain, and many non-Jews and anti-Semites will learn of significant Jewish bloodlines in their past, whether in antiquity, medieval ages, or modernity. Will they then claim something based upon that?
I think you mean significant House of Israel bloodlines. I have no prediction of how this will come about.
I do not know, but it is very, very, likely that the great majority of these have already historically been Christian and thus saved under another method. Those living today may have apostasised like their fellow-former-CINO's-- but they might be just as likely, if they suddenly "got religion," to "get" evangelical Christianity as Judaism, imho.
While I have no prediction, I'm sure that a choice will be given. I don't think that choice has been given to date. Too much ignorance about the nature of things abounds. A true choice can only depend on knowledge.
I am not interested in those views, and I do not expect G-d to do anything in the final ages wrt those nations per se.
I do think that the USA's unhypehenated per se, as the ehrtsot ha-Breet, is/are a sort of second Israel, not according to fleshly descent FTMP, but according to the spirit, and that they/we represent Efraim in the end-time prophecies FWIW.
This is hardly a critical or important matter to me, and I never bother to teach on it.