Hmm. Well you'll probably need for it to have its own version of the Celtic Revival. Perhaps Irish Home Rule is achieved in the mid 19th Century, and it's latched onto as an indication of being loyal subjects but culturally distinct.
Either that or have a Robert Burns type person emerge from the speakers of the language and popularise it.
Either way, the best you can really hope for is something like Scots or Ulster Scots. Culturally distinct certainly, but often neglected in favour of English for official purposes.