Popularity of US College Football in Dublin

"Should we expect lodging to be at a premium in terms of pricing and availability?"
Yes - would be a good weekend to avoid Dublin. Even accommodations distant from the city center will be hard to find at an affordable price.
As an alternative consider going up to Belfast, seeing some of NI, and then flying direct from there to Southampton to join your cruise.

Dublin lodging is always expensive - and when big events like this are on, things cost even more.

Beejaybeeohio,
If you want to go to this game, why not hotel shop and see what rates you can find now. Look for a hotel with a flexible cancellation policy that you can cancel should you decide not to go. I watched part of the Georgia Tech and Florida State game last Saturday and it looked like a really fun event.

For perspective, for this year's game, somewhat over half of the crowd, around 27k, has been estimated to be visitors from the USA.

I looked up attendance for previous years and they do get pretty much a full house (Aviva Stadium is 50 000 capacity) and I was quite surprised. My first thought was along the same lines as Marco's, that the pubs will be full of American folk there for the game.

Thanks all. Now if the Buckeyes were playing, I would love to go to the game!
We are traveling with friends who've not spent as much time as we have in Dublin (owned a timeshare week in Killiney). This info gives me ammunition to convince them we'd be better off staying elsewhere. I'm leaning toward Galway for several reasons: direct bus there from DUB, a chance to visit Cliffs of Moher, etc., and some vrbo options that would accommodate us all with a degree of privacy.