As for a European country official language (strange line to draw), Icelandic is already in a state where younger Icelandic natives speak to each other in English because smartphones do not support their native language. It is entirely possible that Icelandic will be in danger of extinction this century[2].
[1]: https://www.youtube.com/watch?v=t3qbYFvOHwk [2]: https://www.nytimes.com/2017/04/22/world/europe/iceland-icel...