I think the brewpub is a solid business model for Ireland. Having your own outlet means that you are not as dependant on the Irish publican to take your beer. It doesn't mean that you can't sell your beer elsewhere as well, but it means you can eliminate the macro fizz competition form one bar. It might also make publicans more likely to take a tap, as they can see your customers drinking it, so why not theirs?
I think looking at what has already succeeded in Ireland is the way forward and if you look at the most successful micro in the country, the Porterhouse, you will find that it is a brewpub which has grown into a microbrewery and pub chain.
Another example is the Franciscan well. You can now get their beers in quite a few pubs in Cork and further afield, but a very large proportion of their sales is still through their own outlet. Would they have survived the first few years if they had not had that pub?
I know that Biddy Early was also a brewpub and after many years of brewing, it failed but, as the brewer himself said, that has more to do with the decline of the rural pub than with the microbrewery industry. The place is out in the middle of nowhere and it always had to sell macro beer along with the micro brews to get the locals in. I would not advise anyone to buy/open a pub of any kind in a rural area, let alone a brewpub.
In the right location, with decent beer, a well run brewpub is, in my opinion, the best bet for a successful microbrewery in Ireland.