Thought I'd throw my oar in here. I would say we're facing quite a few referendums in the next 5 or 6 years. Perhaps Marriage equality will be one of them, perhaps it won't. I am prepared to speculate on the results of said referendum.

It all depends on what it's combined with on the day to be honest. Obviously there'd have to be more than one referendum/election going on. For the sake of simplicity, let's say that it was a stand alone referendum. In this case I'd see it sailing through, because Irish people tend not to be very anti and those that are anti, are moderately so, so they probably won't bother voting. Where as people who are pro marriage equality would be more inclined to get out and vote.

The only nay voters would be the crazy coir types. All together I wouldn't see turnout being to far above 50%.

Let's say it's combined with something else, a real crowd drawer, that's when it'd become an issue. In that case would it require 2 referendums? 3? Divorce all over again.