I am also hoping ultimately for some matches from Cork relatives, but it may be a long wait. My understanding is that there are relatively few Irish participants in DNA testing in general, and even fewer in Ancestry--look at the relative paucity of trees for people whose families remained in Ireland compared to emigrant families. I have been told (but can't confirm independently) that there are two main reasons for low Irish participation. One is the poor state of the economy and the fact that genealogy is a low priority for many families. The other is that DNA testing in Ireland and Great Britain is seen as tied to law enforcement and is viewed with suspicion by some residents.
I have recently identified three possible 5th cousins in Ireland and, when I get to know them better, hope to get at least one to take a test.