The Famine made Ireland "Irish" in the sense that we understand it today. The famine caused people to become more pious in their Catholicism, even more impoverished and detest the British even more than what they previously did. It probably was the single most important factor in shaping modern Ireland.

Many here are probably aware that Ireland had in 1845 a population of 9 Million but only 6 Million today (all Island pop). The entirety of the UK at the time had a population of 22 Million people. This means the Britain (Scotland, England and Wales) was only 25% bigger than Ireland at that time which is completely different today with the UK having >60 Million people and Ireland (Republic) having 4.5 Million. Ireland had a similar agricultural output compared to Britain which is at least three time larger.

If the famine didn't happen Ireland could easily have a population of over 30 Million. However it did happen and alternate realities are hard to predict.