As someone with a passing academic knowledge of international maritime law... it probably depends on who you ask as to whether it needs to still exist. Typically, the western dominated parts of the UN are opposed to changing established boundaries, as Northern Europe and the US mostly only stand to lose land to erosion, and their few growth areas are typically dangerous active volcanoes a long way from anything of particular value. China, however, likes to point out that if land is there now, there's nothing to say it had to be there last week, which benefits their attempts at resolving the massive territorial snafu of the South China Sea by just piling up a bunch of sand and concrete, then pointing to it and saying 'look, we've got an island here' (the artificial/natural destinction by itself is complicated, because there's a lot of land in many countries that is naturally sea- you can't just up and declare that most of Amsterdam is technically the ocean). Broadly I don't think this one would be massively challenged if we all kept pretending the island was still there- Norway can generally talk to the icelandic government due to them being on good terms whilst Norway is also much bigger and richer. The other contestant would probably be Denmark, but given the claim comes from the proximity of greenland, they might not want to spend millions in a protracted legal case when it's not entirely certain they'll keep greenland in the long term (essentially, if Greenland starts bringing in enough tax, they get to leave Denmark- this was a lot less likely when there was a permanent ice sheet over much of the island, but that might not be the case for long).,(reply>), Also what counts as existing anyway? What if it's still there but just below the surface? (I'm also wondering whether it might erode more slowly once it's fully below the level of the tide)