Credit unions decided to get into current accounts long before Ulster or KBC announced their exits. The guidance was updated by the Central Bank to allow for them in 2016.
Not sure about total take-up but the 2 credit unions I'm a member of offer them and I can see they are loss-making from their annual reports with very limited take-up. I've scanned through a few other reports and the pattern is the same. There were big set-up costs when they introduced them too so even if they do break even it'll take years. Most appear to be charging €48 per annum so I'm not really sure how they even could be making money from them.
Current accounts are also historically loss-making for banks so I don't know how CUs could be making money at such low volumes and economies of scale. The fact that there are 2 providers of current accounts for credit unions is even more mind-boggling. I just don't get what's in it for them really. I don't think any of them could have really believed they would gain significant market share or that current accounts were going to help them in addressing their main issue i.e. that they can't lend enough of the money the take in as savings from members.