He ruled for 3,514 years and marches off to the biggest war in ages were, when he falls, the Noldor Kingdom in exile also fails.
Isn't producing an heir part of a king's (let alone a so-called High King's) duty? So when he "cuts and runs' on his dynastic duty, it was history for the Noldor Kingdom in exile.
My original question was to see if there was an explination in the Lost Tales or JRRT Letters. My theory is that they lost so many Elves (including Gil-galad) that, like Arnor, only worse, the Elf Kingdom could no longer sustain itself. The few survivors that didn't bug out to the West would have settled with Elrond or Cirdan. Lorien was home of the Silvan Elves and they 'imported' Galadriel (Noldor) and Celeborn (Sindar) to rule after Amroth was lost at sea.