Did Elrond have a right to the throne of Númenor?

Question

In case the line of the Kings of Númenor would have gone extinct, would Elrond Half-elven, being the brother of Númenor's first king Elros Tar-Minyatur, have had a right to the throne of Númenor, or was this right forfeit as he chose to be an Elf, not a Man? If Elrond wouldn't have the right, would Arwen have it as she chose mortality (if Númenor wouldn't have sunk)?

And would the Lords of Andúnië have more right to the throne than Elrond? They're direct descendants of Númenórean kings but through the female line. Eventually there was absolute primogeniture in Númenor, but Elrond would still have more right if he didn't choose immortality, wouldn't he (he wouldn't be alive anymore of course, just theoretically)? In case the direct line got extinct, would Númenor's law favor the Lords of Andúnië or would it favor Elrond? And what about the law prior to allowing Ancalimë become queen?

Answer 1

How would all the descendants of Elros die out?

Depending on when it would have happened, there could have been tens, hundreds, thousands, tens of thousands, etc., known descendants of Elros in Númenor. The Kingdom of Númenor lasted for about three thousand years, and even though Númenórean genrations were long, there should have been at least twenty Númenórean generations. If the descendants of Elros doubled in each generation, there would have been a million members of the 20th generation.

Well, maybe all the descendants of Elros in the male line, or even all the descendants of Elros including female line descendants, could gather in one building for some very special ceremony, such as the installation of a new king. And maybe an earthquake could knock the building down and crush them all to death.

If that was after the Númenórians began fighting Sauron in Middle-earth, Sauron might have found a way to cause a terrible, devastating earthquake in Númenor, and timing it to take out the entire dynasty at once might have been possible.

There are examples of thrones being peacefully inherited by people not descended from the first ruler.

The best European example that comes to mind is the Roman Empire. It was founded by Augustus, who intended from the first to make the leadership hereditary in his family, but the Julio-Claudian dynasty of his relatives and descendants ended with Nero in AD 68. There were surviving Roman aristocrats descended from the daughter of Augustus, and occasionally one of them would become emperor, usually for other reasons than descent from Augustus. The latest emperor claimed to be descended from Augustus was Gordian III who reigned from 238 to 244.

And of course some later emperors might have also been descended from Augustus without that fact being known now or maybe even during their reigns. But of course if nobody knew they were descended from Augustus that would not have been a factor in making them emperor.

So if the descendants of Elros died out in Númenor, the people of Númenor might have chosen a new dynasty, or chosen to make the position of king elective, or maybe they would have selected Elrond, the closest relative to Elros the first king, to be their king.

It is possible the Númenóreans might have selected Elrond to be the eternal king of Númenor, with the island actually governed in Elrond's name by a series of more temporary co-kings or maybe viceroys, Men and/or Elves selected by Elrond and/or the Númenóreans.

Answer 2

Elrond and Arwen, it seems not.

From Unfinished Tales, Aldarion and Erendis, The Further Course of the Narrative:

It was understood that if there were no son the nearest male kinsman of male descent from Elros Tar-Minyatur would be the Heir. [...] But by the 'new law' the (eldest) daughter of the Ruler inherited the Sceptre, if he had no son

whereas LOTR Appendix A says that the new law was...

that the eldest child of the King, whether man or woman, should receive the sceptre.

Despite this inconsistency, descent seems to be reckoned from Elros and Elrond is not a descendant of Elros.

The Lords of Andunie would, however, be possible heirs (at least after the change of law, through Silmarien) if all the closer heirs were gone.

However, if all legally possible heirs were dead, Elrond would certainly be a plausible choice for a new king, founding a new dynasty - though it's likely he would refuse.

After all, Elrond could probably have claimed an Elvish kingship, being directly descended from both Turgon and Thingol, but never did - he's called "Lord of Rivendell" not "King".