[Taeolas]

Just a guess and not knowing the history well; but I suspect NS Gaelic died off so much because it didn't have its own Quebec within the Canadian framework to keep it alive.

French outside of Quebec (and NB) has had hard times, but they are constantly reinforced by having such a large pool of French available in La Belle Province. So even if local support falters, there is still exposure from Quebec News and Quebec TV channels and papers and what not, to help keep it on life support.

Gaelic, outside of NS and within Canada, is effectively non-existent. So if it isn't supported, if there isn't a Canal Gaelic or two in the cable packages, a Gaelic news paper from a big Gaelic Metro, it makes it harder to keep it around.

So to keep Gaelic alive as a language, I suppose you would have to look at making Sydney much bigger and much more Gaelic in the early years; a stronger Scottish influence all around maybe. (Maybe some sort of Scottish famine similar to the Irish Famine that lead to Scots looking for better lives across the seas?)