Why was the Irish language so unique among non-state languages in Europe in the way it went into decline so early in comparison? Irish started to decline in the east of Ireland in the late 18th century and was a minority language nationally by the mid 19th century, and spoken by only 15% of people by the end of British rule. Contrast that to the regional languages of France, (except for those closest to Paris), which didn't really go into decline until the 20th century, to the regional languages of Spain such as Catalan which is still going strong, or to the then non-state languages of Eastern Europe such as Czech, Polish, Finnish etc which, upon their independence after WW1 became national languages like any other.
Even compared to other Celtic languages of the United Kingdom, Irish fell prematurely; the decline of Scottish Gaelic within the Highlands was largely within a late c19-early c20 timeline while within the Western Isles it is ongoing. Welsh only became a minority language within Wales in 1900 with large scale English immigration and is still a majority language in the North-West in 2016.
Thus what would need to change in ATL for most of the then non-state languages across Europe to decline like Irish did, in a timeline stretching from 1780-1914? This includes the Austro-Hungarian Empire etc.
Even compared to other Celtic languages of the United Kingdom, Irish fell prematurely; the decline of Scottish Gaelic within the Highlands was largely within a late c19-early c20 timeline while within the Western Isles it is ongoing. Welsh only became a minority language within Wales in 1900 with large scale English immigration and is still a majority language in the North-West in 2016.
Thus what would need to change in ATL for most of the then non-state languages across Europe to decline like Irish did, in a timeline stretching from 1780-1914? This includes the Austro-Hungarian Empire etc.