There are a number of trees on Ancestry which list this family. All indicate the family moved to the Glasgow area around 1864. John & Sarah were in the 1891 census for 102 King St, Govan, Glasgow in 1891 and seem to have disappeared after that. There is mention of John’s sister Ellen dying in Rutherglen in 1887, a brother James dying in Wigton, Cumberland in 1903, a sister Elizabeth dying in Ballymena in 1914 and a son John dying in New Zealand in 1924. So the general impression is that the family had largely died out in Ireland, save for Elizabeth’s family.
If you contact the various tree owners you may get more information on where their children went.
Here’s the Elizabeth Kernoghan who died in 1914 in the 1901 Irish census. She was married, but it appears her maiden name was Kernoghan. She married William Kernoghan in 1846, at Ahoghill 1st which would suggest that was the family church:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_re…
http://www.census.nationalarchives.ie/pages/1901/Antrim/Ahoghill/Killane/924015/
1911 census:
http://www.census.nationalarchives.ie/pages/1911/Antrim/Ahoghill/Killan…
Probate of the Will of Elizabeth Kernohan late of Killane Ahoghill County Antrim Widow who died 4 May 1915 granted at Belfast to John Kernohan and Robert Kernohan Farmers
Administration of the Estate of John Kernohan late of Killane County Antrim Farmer who died 13 June 1917 granted at Belfast to Robert Kernohan Farmer
Kernohan Robert of Killane county Antrim farmer died 7 October 1943 Probate Belfast 28 January to George B. Caruth solicitor. Effects £400 15s.
The above probate files are in PRONI in Belfast. They may give details of next of kin (in the last 100 – 80 years anyway). One concern I would have is that this Elizabeth’s father John was a farmer in 1846, and the family apparently lived in KIllane. However when John married Sarah Grant in 1853, the father John was a weaver (a completely different profession), and the family were in Galgorm Parks. So I am not convinced this is the same John Kernoghan. I suspect 2 different families may have been mixed up, because both had a father named John.