Quite a few will say there is nothing to worry about "We love the Irish", anyone of Irish nationality can stay, work, etc. to heart's content forever. Others will quote own experience of having Indefinite Leave to Stay, a Home Office letter to that effect and a stamp in the passport to the same effect but still being told it has "expired, on yer bike". Today No.10 said there will be no automatic expulsions of EU nationals, settled status or not, implying that some/many/all may be allowed to remain (against the will of 17 million people, democracy, etc., just like the upcoming border between Northern Ireland and Great Britain). There will inevitably be those who will advise your friend not to believe a word of what the establishment says because they make it up as they go along since they basically are all at sea.