It's hard to say. There's so many potential PODs, that are themselves somewhat limited and balanced by likely English/French reactions and economic or political issues that it's hard to give a definite answer without creating a concrete timeline to back it up.
As far as Irish Gaelic goes, there's a couple of things. The most recent thing is to do something about the Potato Famine. It was poor Gaelic speaking peasants that tended to suffer the most due to poverty and starvation that resulted and thus needed to emigrate outside of Ireland, so a more limited or nonexistant Potato Famine preserves a much larger population of Gaelic speakers(or at least people familiar with Irish Gaelic) that when/if independence movements come around they'll have a lot more to work with in that sense than OTL did. IOTL, one of the major reasons for changing to English was to encourage the poor desperate peasants to have the skills necessary to get those (relatively) well-paying factory jobs in English speaking Britain or America and send back remittances.
That's not to say that the ruling class won't use English, or that English wouldn't be a very useful language to learn given professional opportunities. However, Swiss German, Catalan, and Galician all managed to hold on despite having similar predictions and being much closer in language to the established state that ruled over them, and all have managed to continue to exist as dominant forces in their region. I can see Gaelic developing in a similar way, being the language of every day life even for those that go speak English at work.
As far as Irish Gaelic goes, there's a couple of things. The most recent thing is to do something about the Potato Famine. It was poor Gaelic speaking peasants that tended to suffer the most due to poverty and starvation that resulted and thus needed to emigrate outside of Ireland, so a more limited or nonexistant Potato Famine preserves a much larger population of Gaelic speakers(or at least people familiar with Irish Gaelic) that when/if independence movements come around they'll have a lot more to work with in that sense than OTL did. IOTL, one of the major reasons for changing to English was to encourage the poor desperate peasants to have the skills necessary to get those (relatively) well-paying factory jobs in English speaking Britain or America and send back remittances.
That's not to say that the ruling class won't use English, or that English wouldn't be a very useful language to learn given professional opportunities. However, Swiss German, Catalan, and Galician all managed to hold on despite having similar predictions and being much closer in language to the established state that ruled over them, and all have managed to continue to exist as dominant forces in their region. I can see Gaelic developing in a similar way, being the language of every day life even for those that go speak English at work.