For those of you who had chatted about this some time back...there is possibly going to be an update to the Catholics-only policy, or whatever form that policy takes, in the near future.
It seems like they're proposing scrapping it, or modifying it, to allow for non-catholic kids to attend those schools. There's talk of a 'catchment area' policy too which is probably something similar to how the US system works, whereby preference is given to local kids.
Some details at these links:
Removing 'Baptism Barrier' from schools still an uphill task: http://www.rte.ie/news/analysis-and-comment/2017/0118/845852-baptism-barrier/
School baptism rule to be scrapped: http://www.independent.ie/irish-news/education/school-baptism-rule-to-be-scrapped-35370031.html