I think any sort of diversity is good, but as we've seen, the Irish market seems to have an endless capacity to support crap lager.
This seems to be just about Carling, which they spend a fortune on in the UK and which was once a big brand in Ireland. I'm guessing they may want to take Coors Light back when that contract expires -- depending on whether they make more money from importing it from the UK and selling direct, as against taking Heineken's licence fee as handy money.
I doubt we'll see a big new range of beers any more than Irish Tescos are comparable with UK ones for beer diversity.
Edit: But hey, we'll have an address in Maynooth to write to to demand White Shield <!-- s:D --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="

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Edit edit: Kasteel Cru is at saturation point on the UK market. I can see them wanting to do the same here.